COMPOSITIONS USEFUL AS REFRIGERANTS

Abstract: A refrigerant composition comprising a mixture of difluoromethyl trifluoromethyl ether and at least one hydrofluoroalkane selected from difluoromethane, pentafluoroethane and 1,1,1-trifluoroethane is claimed.

Description: COMPOSITIONS USEFUL AS REFRIGERANTS. The present invention relates generally to refrigerant compositions for cooling and heating applications and to the use of such compositions in heat transfer devices. More particularly, the present invention is concerned with refrigerant compositions which are designed to replace chlorodifluoromethane (Refrigerant R-22) and the azeotropic mixture of chlorodifluoromethane with chloropentafluoroethane (Refrigerant R-115), the azeotrope being Refrigerant R-502. Mechanical refrigeration systems and related heat transfer devices such as heat pumps and air-conditioning systems are well known. In such devices, a refrigerant liquid of a suitable boiling point evaporates at low pressure taking heat from a surrounding zone. The resulting vapour is then compressed and passed to a condenser where it condenses and gives off heat to a second zone, the condensate being returned through an expansion valve to the evaporator, so completing the cycle. The mechanical energy required for compressing the vapour and pumping the liquid may be provided by an electric motor or an internal combustion engine. In addition to having a suitable boiling point and a high latent heat of vaporisation, the properties preferred of a refrigerant include low toxicity, non- flammability, non-corrosivity, high stability and freedom from objectionable odour. Hitherto, heat transfer devices have tended to use fully and partially halogenated chlorofluorocarbon refrigerants such as chlorodifluoromethane (Refrigerant R-22) or the azeotropic mixture of chlorodifluoromethane and chloropentafluoroethane (Refrigerant R-502). In recent years, however, there has been increasing international concern that the fully and partially halogenated chlorofluorocarbons may be damaging the earth's protective ozone layer and there is general agreement that their manufacture and use should be severely restricted and eventually phased out completely. Whilst heat transfer devices of the type to which the present invention relates are essentially closed systems, loss of refrigerant to the atmosphere can occur due to leakage during operation of the equipment or during maintenance procedures. It is important, therefore, to replace fully and partially halogenated chlorofluorocarbon refrigerants by materials having substantially lower, preferably zero, ozone depletion potentials . In addition to the possibility of ozone depletion, it has been suggested that significant concentrations of chlorofluorocarbon refrigerants in the atmosphere might contribute to global warming (the so-called greenhouse effect). It is desirable, therefore, to use refrigerants which have relatively short atmospheric lifetimes as a result of their ability to react with other atmospheric constituents such as hydroxyl radicals . The present invention provides a refrigerant composition which may be used in place of Refrigerants R-22 and R-502. The composition contains refrigerant compounds which have essentially zero ozone depletion potentials and comparatively low direct global warming potentials . Accordingly, the present invention provides a refrigerant composition comprising a mixture of difluoromethyl trifluoromethyl ether (CF3OCHF2) and at least one hydrofluoroalkane selected from difluoromethane CH2 2). pentafluoroethane (CF3CHF2) and 1,1 ,1-trifluoroethane (CF3CH 3 ). Refrigerant compositions in accordance with the present invention typically contain from 5 to 952 by weight of difluoromethyl trifluoromethyl ether and from 95 to 5Z by weight of the hydrofluoroalkane component. Suitable refrigerant compositions may contain a single hydrofluoroalkane selected from the three specified compounds or a mixture of any two or all three of the said hydrofluoroalkanes . Additionally, the refrigerant compositions of the invention may contain other refrigerant compounds which have low and preferably zero ozone depletion potentials, for example other hydrofluoroalkanes and/or other fluorinated ethers containing residual hydrogen atoms. Examples of other hydrofluoroalkanes which may be incorporated in the refrigerant compositions of the invention include 1,1,1, 2-tetrafluoroethane (R-134a ) , 1,1,2,2-tetrafluoroethane (R-134) and 1, 1-difluoroethane (R-152a). Examples of other fluorinated ethers which may be included in the refrigerant compositions of the invention are the fluorinated dimethyl ethers containing residual hydrogen atoms. Although the refrigerant compositions of the invention may comprise other refrigerant compounds, the preferred refrigerant compositions consist essentially of difluoromethyl trifluoromethyl ether and at least one hydrofluoroalkane selected from difluoromethane (R-32), pentafluoroethane (R-125) and 1,1,1-trifluoroethane (R-143a). Although the refrigerant compositions of the invention may be zeotropic they are preferably azeotropic or azeotrope-like. The preferred refrigerant compositions of the invention comprise a mixture of difluoromethyl trifluoromethyl ether and difluoromethane, since such compositions may provide a particularly suitable alternative to Refrigerants R-22 and R-502. Such compositions may additionally comprise one or more further refrigerant compounds, such as pentafluoroethane and/or 1, 1,1-trifluoroethane and/or at least one other fluorinated ether containing residual hydrogen atoms and/or at least one other hydrofluoroalkane. However, particularly preferred refrigerant compositions are mixtures consisting essentially of difluoromethyl trifluoromethyl ether and di luoromethane, since such compositions, in particular, can exhibit a performance in a heat transfer device which is comparable to Refrigerants R-22 and R-502. Refrigerant compositions according to the invention containing from 20 to 80 Z by weight of difluoromethyl trifluoromethyl ether and from 80 to 20 Z by weight of difluoromethane are preferred as a replacement for Refrigerant R-502. As a R-502 replacement, refrigerant compositions of the invention containing from 40 to 80 Z by weight of difluoromethyl trifluoromethyl ether and from 60 to 20 Z by weight of difluoromethane are preferred, with compositions containing from 50 to 75 Z by weight of difluoromethyl trifluoromethyl ether and from 50 to 25 Z by weight of difluoromethane being particularly preferred. An especially preferred refrigerant composition for replacing R-502 contains from 50 to 70 Z by weight of difluoromethyl trifluoromethyl ether and from 50 to 30 Z by weight of difluoromethane. Tables 1 to 3 show the results of analysing the performance of a number of refrigerant compositions of the invention in a low temperature refrigeration cycle to assess the suitability thereof as a replacement for R-502. All the compositions analysed comprised difluoromethyl trifluoromethyl ether (E-125 in the Tables) and difluoromethane (R-32 in the Tables) in varying amounts. The percentage by weight of each component in the refrigerant compositions analysed is given in the second row of the Tables. Thus, the results of analysing the performance of the following refrigerant compositions are given in Tables 1 to 3: (1) A composition comprising 75 Z by weight of difluoromethane and 25 Z by weight of difluoromethyl trifluoromethyl ether. (2) A composition comprising 50 Z by weight of difluoromethane and 50 Z by weight of difluoromethyl trifluoromethyl ether. (3) A composition comprising 25 Z by weight of difluoromethane and 75 Z by weight of difluoromethyl trifluoromethyl ether. (4) A composition comprising 30 Z by weight of difluoromethane and 70 Z by weight of difluoromethyl trifluoromethyl ether. (5) A composition comprising 35 Z by weight of difluoromethane and 65 Z by weight of difluoromethyl trifluoromethyl ether. Three different sets of operating conditions were used for the analysis. These conditions were as follows : Set 1: Evaporator Temperature: -40°C Condenser Temperature: 32°C Superheat: 58°C Subcooling: 0°C Cooling Duty: 1 KW Isentropic Compressor Efficiency: 100 z The results of analysing the various refrigerant compositions in a low temperature refrigeration cycle using these operating conditions are given in Table 1. Set 2: Evaporator Temperature: -32°C Condenser Temperature: 43°C Superheat: 50°C Subcooling: 0°C Cooling Duty: 1 KW Isentropic Compressor Efficiency: 100 Z The results of analysing the various refrigerant compositions in a low temperature refrigeration cycle using these operating conditions are given in Table 2. Set 3: Evaporator Temperature: -40°C Condenser Temperature: 54°C Superheat: 58°C Subcooling: 0°C Cooling Duty: 1 KW Isentropic Compressor Efficiency: 100 Z The results of analysing the various refrigerant compositions in a low temperature refrigeration cycle' using these operating conditions are given in Table 3. The performance parameters of the refrigerant compositions which are presented in Tables 1 to 3, i.e. condenser pressure, evaporator pressure, discharge temperature, return gas temperature, volumetric flow, system efficiency (coefficient of performance, by which is meant the ratio of cooling duty achieved to mechanical energy supplied to the compressor), refrigeration capacity (cooling duty per unit swept volume of the compressor), and the glide in the evaporator (the temperature range over which the refrigerant composition boils in the evaporator), are all art recognised parameters. The values for the coefficient of performance shown in the Tables do not take account of superheat. The performance of Refrigerant R-502 and difluoromethane under the three different sets of operating conditions are also shown in the Tables by way of comparison. From Tables 1 to 3, it is apparent that refrigerant compositions according to the invention comprising difluoromethyl trifluoromethyl ether and difluoromethane can exhibit a performance in a low temperature refrigeration system which is comparable to that of Refrigerant R-502. If difluoromethane is used as the sole refrigerant in a refrigeration system, high energy efficiencies and high refrigeration capacities relative to Refrigerant R-502 are obtained, as shown by the values for the coefficient of performance and the cooling duty per unit swept volume of the compressor. However, the discharge temperatures, condenser pressures and evaporator pressures which are obtained with difluoromethane are also high and are not ideal when one is looking for a replacement for Refrigerant * R-502. The addition of difluoromethyl trifluoromethyl ether to the difluoromethane provides a means of reducing the discharge temperature, condenser pressure and evaporator pressure while retaining energy efficiencies and refrigeration capacities which are still comparable with and in certain cases superior to R-502. Furthermore, the glide in the evaporator for all the mixed refrigerant compositions tested was 1.4°C or less showing that such compositions are azeotrope like. Refrigerant compositions according to the invention containing from 25 to 99 Z , e.g. 50 to 99 Z, by weight of difluoromethyl trifluoromethyl ether and from 75 to 1 Z, e.g. 50 to 1 Z, by weight of difluoromethane are preferred as a replacement for Refrigerant R-22, particularly in air conditioning applications. A more preferred refrigerant composition for replacing R-22 in air conditioning applications contains from 70 to 90 Z by weight of difluoromethyl trifluoromethyl ether and from 30 to 10 Z by weight of difluoromethane. A particularly preferred refrigerant composition for replacing R-22 in air conditioning applications contains from 75 to 90 Z by weight of difluoromethyl trifluoromethyl ether and from 25 to 10 Z by weight of difluoromethane. Tables 4 and 5 show the results of analysing the performance of a number of refrigerant compositions of the invention in a refrigeration cycle to assess the suitability thereof as a replacement for R-22 in air « conditioning applications. All the compositions 5 analysed comprised difluoromethyl trifluoromethyl ether t (E-125 in the Tables) and difluoromethane (R-32 in the Tables) in varying amounts. The percentage by weight of each component in the refrigerant compositions analysed is given in the second row of the Tables. Thus, the results of analysing the performance of the following 10 refrigerant compositions are given in Tables 4 and 5: (1) A composition comprising 75 Z by weight of difluoromethane and 25 Z by weight of difluoromethyl trifluoromethyl ether. 15 (2) A composition comprising 50 Z by weight of difluoromethane and 50 Z by weight of difluoromethyl trifluoromethyl ether. (3) A composition comprising 25 Z by weight of difluoromethane and 75 Z by weight of 20 difluoromethyl trifluoromethyl ether. (4) A composition comprising 20 Z by weight of difluoromethane and 80 Z by weight of difluoromethyl trifluoromethyl ether. (5) A composition comprising 15 Z by weight of 25 difluoromethane and 85 Z by weight of difluoromethyl trifluoromethyl ether. Two different sets of operating conditions were used for the analysis. The conditions used reflect the 30 conditions which are likely to prevail in air conditioning systems using R-22 as the refrigerant. The two sets of conditions were as follows: Set 4: 35 Evaporator Temperature: 4.44°C Condenser Temperature: 37.78°C Superheat: 11.11°C Subcooling: 0°C Cooling Duty: 1 KW Isentropic Compressor Efficiency: 75 Z The results of analysing the various refrigerant compositions in a refrigeration cycle using these operating conditions are given in Table 4. Set 5: Evaporator Temperature: 8.89°C Condenser Temperature: 37.78°C Superheat: 11.11°C Subcooling: 8.83°C Cooling Duty: 1 KW Isentropic Compressor Efficiency: 75 Z The results of analysing the various refrigerant compositions in a refrigeration cycle using these operating conditions are given in Table 5. The performance parameters which appear in Tables 4 and 5 are the same as those presented in Tables 1 to 3. However, the values for the coefficient of performance given in Tables 4 and 5 take account of superheat. The performance of Refrigerant R-22 and difluoromethyl trifluoromethyl ether under the two different sets of operating conditions are also shown in Tables 4 an 5 by way of comparison. From Tables 4 and 5, it is apparent that refrigerant compositions according to the invention comprising difluoromethyl trifluoromethyl ether and difluoromethane can exhibit a performance in an air conditioning system which is similar to that of Refrigerant R-22. It is also evident that refrigerant compositions containing from 75 to 90 Z by weight of difluoromethyl trifluoromethyl ether and from 25 to 10 Z by weight of difluoromethane, especially from 75 • to 85 Z by weight of difluoromethyl trifluoromethyl ether and from 25 to 15 Z by weight of difluoromethane, offer a good alternative to Refrigerant R-22 in air conditioning applications . The refrigerant compositions of the invention may be prepared by a simple mixing process. The compositions are useful in all types of compression cycle heat transfer devices. Thus, they m_.T be used to provide cooling by a method involving condensing the refrigerant composition and thereafter evaporating it in a heat exchange relationship with a body to be cooled. They may also be used to provide heating by a method involving condensing the refrigerant composition in a heat exchange relationship with a body to be heated and thereafter evaporating it. The compositions of the invention provide a good compromise between atmospheric lifetime, ozone depletion, discharge temperature, working pressure and efficiency. They are especially suitable as replacements for R-22 and the R-502 azeotrope. TABLE 1 REFRIGERANT R-502 R-32 ' R-32/E-125 Z BY WEIGHT 100 100 75/25 50/50 25/75 CONDENSER PRESSURE (Bar) 13.89 20.31 19.12 17.38 14.75 EVAPORATOR PRESSURE (Bar) 1.31 1.78 1.67 1.51 1.26 DISCHARGE TEMPERATURE (°C) 110.8 176.5 150.5 126.1 104.2 RETURN GAS TEMPERATURE (°C) 18.0 18.0 18.2 18.5 18.7 VOLUMETRIC FLOW (M 3 /s x 102) 0.180 0.100 0.118 0.141 0.184 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 555 1000 847 709 543 COEFFICIENT OF PERFORMANCE 1.64 1.78 1.74 1.68 1.59 BOILING BP* -45.6 -51.7 -51.07 -49.64 -46.91 POINT (°C) DP** -45.6 -51.7 -50.63 -48.32 -44.43 GLIDE IN EVAPORATOR (°C) 0 0 0.4 1.0 1.4 * BP = Bubble Point ** DP = Dew Point TABLE 1 CONTINUED REFRIGERANT R-502 R-32 R-32/E-125 Z BY WEIGHT 100 100 30/70 35/65 CONDENSER PRESSURE (Bar) 13.89 20.31 15.22 15.95 EVAPORATOR PRESSURE (Bar) 1.31 1.78 1.32 1.37 DISCHARGE TEMPERATURE (°C) 110.8 176.5 108.5 112.8 RETURN GAS TEMPERATURE (°C) 18.0 18.0 18.7 18.7 VOLUMETRIC FLOW (M 3 /s x 102) 0.180 0.100 0.172 0.163 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 555 1000 581 613 COEFFICIENT OF PERFORMANCE 1.64 1.78 1.61 1.63 BOILING BP* -45.6 ■51.7 -47.65 -48.31 POINT (°C) DP** -45.6 ■51.7 -45.36 -46.22 GLIDE IN EVAPORATOR (°C) 0 1.4 1.3 * BP - Bubble Point ** DP - Dew Point TABLE 2 REFRIGERANT R- 502 R- 32 R- 32 / E- 125 Z BY WEIGHT 100 100 75 / 25 50 / 50 25 / 75 CONDENSER PRESSURE (Bar) 18.02 26.70 25.15 22.89 19.41 EVAPORATOR PRESSURE (Bar) 1.84 2.52 2.37 2.13 1.78 DISCHARGE TEMPERATURE (°C) 110.3 173.4 149.2 125.9 104.6 RETURN GAS TEMPERATURE (°C) 18.0 18.0 18.2 18.5 18.7 VOLUMETRIC FLOW (M 3 /s x 102) 0.140 0.080 0.092 0.112 0.148 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 714 1250 1087 893 676 COEFFICIENT OF PERFORMANCE * 1.55 1.73 1.64 1.57 1.46 BOILING BP* -45.6 -51.7 -51.07 -49.64 -46.91 POINT (°C) DP** -45.6 -51.7 -50.63 -48.32 -44.43 GLIDE IN EVAPORATOR (°C) 0 0 0.4 1.0 1.3 * BP = Bubble Point ** DP - Dew Point TABLE 2 CONTINUED REFRIGERANT R- 502 R- 32 R - 32 / E - 125 Z BY WEIGHT 100 100 30 / 70 35 / 65 CONDENSER PRESSURE (Bar) 18.02 26.70 20.15 21.07 EVAPORATOR PRESSURE (Bar) 1.84 2.52 1.86 1.94 DISCHARGE TEMPERATURE (°C) 110.3 173.4 108.7 113.2 RETURN GAS TEMPERATURE (°C) 18.0 18.0 18.6 18.6 VOLUMETRIC FLOW (M 3 /s x 102) 0.140 0.080 0.138 0.131 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 714 1250 725 763 COEFFICIENT OF PERFORMANCE 1.55 1.73 1.49 1.50 BOILING BP* -45.6 -51.7 -47.65 -48.31 POINT (°C) DP** -45.6 -51.7 -45.36 -46.22 GLIDE IN EVAPORATOR (°C) 0 0 1.4 1.3 * BP - Bubble Point ** DP = Dew Point TABLE 3 REFRIGERANT R- 502 R- 32 R- 32 / E-125 Z BY WEIGHT 100 100 75 / 25 50 / 50 25 / 75 CONDENSER PRESSURE (Bar) 23.01 34.50 32.53 29.70 25.11 EVAPORATOR PRESSURE (Bar) 1.31 1.78 1.67 1.50 1.25 DISCHARGE TEMPERATURE (°C) 135.3 216.7 184.4 154.5 127.2 RETURN GAS TEMPERATURE (°C) 18.0 18.0 18.1 18.4 18.4 VOLUMETRIC FLOW (M 3 /s x 102) 0.250 0.130 0.162 0.207 0.298 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 400 769 617 483 336 COEFFICIENT OF PERFORMANCE 0.92 1.13 1.00 0.92 0.80 BOILING BP* -45.6 -51.7 -51.07 -49.64 -46.91 POINT (°C) DP** -45.6 -51.7 -50.63 -48.32 -44.43 GLIDE IN EVAPORATOR (°C) 0 0 0.3 0.7 0.9 * BP *■ Bubble Point ** DP = Dew Point TABLE 3 CONTINUED REFRIGERANT R-502 R-32 R-32/E-125 Z BY WEIGHT 100 100 30/70 35/65 CONDENSER PRESSURE (Bar) 23.01 34.50 26.19 27.06 EVAPORATOR PRESSURE (Bar) 1.31 1.78 1.31 1.36 DISCHARGE TEMPERATURE CO 135.3 216.7 132.5 137.7 RETURN GAS TEMPERATURE (°C) 18.0 18.0 18.5 18.5 VOLUMETRIC FLOW (M 3 /s x 102) 0.250 0.130 0.273 0.251 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 400 769 366 398 COEFFICIENT OF PERFORMANCE 0.92 1.13 0.83 0.86 BOILING BP* -45.6 ■51.7 •47.65 •48.31 POINT (°C) DP** -45.6 •51.7 •45.36 ■46.22 GLIDE IN EVAPORATOR (°C) 0.9 0.9 * BP - Bubble Point ** DP - Dew Point TABLE 4 REFRIGERANT R- 22 E- 125 R- 32 / E- 125 Z BY WEIGHT 100 100 75 / 25 50 / 50 25 / 75 CONDENSER PRESSURE (Bar) 14.50 12.80 22.14 20.31 17.0.7 EVAPORATOR PRESSURE (Bar) 5.70 5.00 8.80 7.95 6.68 DISCHARGE TEMPERATURE (°C) 74.3 49.4 80.0 70.7 60.7 RETURN GAS TEMPERATURE ( β C) 15.5 15.5 15.8 16.4 16.8 VOLUMETRIC FLOW (M 3 /s x 102) 0.027 0.035 0.019 0.022 0.026 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 3708 2857 5263 4545 3846 COEFFICIENT OF PERFORMANCE 5.19 4.83 4.85 4.78 4.88 BOILING BP* -41.0 -38.4 -50.07 -49.64 -46.91 POINT (°C) DP** -41.0 -38.4 -50.63 -48.32 -44.43 GLIDE IN EVAPORATOR (°C) 0 0 0.6 1.6 2.4 * BP = Bubble Point ** DP - Dew Point TABLE 4 CONTINUED REFRIGERANT R- 22 E- 125 R- 32 / E- 125 Z BY WEIGHT 100 100 20 / 80 15 / 85 CONDENSER PRESSURE (Bar) 14.50 12.80 16.31 15.40 EVAPORATOR PRESSURE (Bar) 5.70 5.00 6.37 6.03 DISCHARGE TEMPERATURE (°C) 74.3 49.4 58.8 56.4 RETURN GAS TEMPERATURE (°C) 15.5 15.5 16.7 16.6 VOLUMETRIC FLOW (M 3 /s x 10∑) 0.027 0.035 0.028 0.030 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 3708 2857 3571 3333 COEFFICIENT OF PERFORMANCE 5.19 4.83 4.87 4.91 BOILING BP* -41.0 -38.4 -46.01 -44.88 POINT (°C) DP** -41.0 -38.4 -43.41 -42.30 GLIDE IN EVAPORATOR (°C) 0 0 2.4 2.1 * BP - Bubble Point ** DP - Dew Point TABLE 5 REFRIGERANT R-22 E-125 R-32/E-125 Z BY WEIGHT 100 100 75/25 50/50 25/75 CONDENSER PRESSURE (Bar) 14.50 12.80 22.14 20.31 17.07 EVAPORATOR PRESSURE (Bar) 6.60 5.75 10.09 9.13 7.70 DISCHARGE TEMPERATURE (°C) 70.4 49.28 75.5 67.8 59.3 RETURN GAS TEMPERATURE (°C) 20.0 20.0 20.3 20.9 21.5 VOLUMETRIC FLOW (M 3 /s x 102) 0.022 0.026 0.015 0.017 0.020 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 4560 3846 6667 5882 5000 COEFFICIENT OF PERFORMANCE 6.60 6.54 6.32 6.29 6.52 BOILING BP* -41.0 -38.4 -51.07 -49.64 -46.91 POINT (°C) DP** -41.0 -38.4 -50.63 -48.32 -44.43 GLIDE IN EVAPORATOR CO 0 0 0.6 1.8 2.9 * BP - Bubble Point ** DP » Dew Point TABLE 5 CONTINUED REFRIGERANT R-22 E-125 R-32/E-125 Z BY WEIGHT 100 100 20/80 15/85 CONDENSER PRESSURE (Bar) 14.50 12.80 16.31 15.40 EVAPORATOR PRESSURE (Bar) 6.60 5.75 7.34 6.97 DISCHARGE TEMPERATURE CO 70.4 49.28 57.6 55.6 RETURN GAS TEMPERATURE CO 20.0 20.0 21.4 21.3 VOLUMETRIC FLOW (M 3 /s x 102) 0.022 0.026 0.021 0.023 COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 ) 4560 3846 4762 4348 COEFFICIENT OF PERFORMANCE 6.60 6.54 6.54 6.62 BOILING BP* 41.0 38.4 POINT CO DP** 41.0 38.4 GLIDE IN EVAPORATOR (°C) 2.8 2.6 * BP - Bubble Point ** DP - Dew Point

Claims: Claims : 1. A refrigerant composition comprising a mixture of difluoromethyl trifluoromethyl ether and at least one hydrofluoroalkane selected from difluoromethane, pentafluoroethane and 1,1,1-trifluoroethane. 2. A refrigerant composition as claimed in claim 1, • characterised in that it comprises a mixture of difluoromethyl trifluoromethyl ether and difluoromethane. 3. A refrigerant composition as claimed in claim 2, characterised in that it consists essentially of difluoromethyl trifluoromethyl ether and difluoromethane . 4. A refrigerant composition as claimed in claim 2 or claim 3, characterised in that it comprises from 5 to 95 Z by weight of difluoromethyl trifluoromethyl ether and from 95 to 5 Z by weight of difluoromethane. 5. A refrigerant composition as claimed in any one of claims 2 to 4, characterised in that it comprises from 20 to 80 Z by weight of difluoromethyl trifluoromethyl ether and from 80 to 20 Z by weight of difluoromethane. 6. A refrigerant composition as claimed in any one of claims 2 to 5, characterised in that it comprises from 40 to 80 Z by weight of difluoromethyl tri luoromethyl ether and from 60 to 20 Z by weight of difluoromethane. 7. A refrigerant composition as claimed in any one of claims 2 to 6, characterised in that it comprises from 50 to 75 Z by weight of difluoromethyl trifluoromethyl ether and from 50 to 25 Z by weight of difluoromethane. 8. A refrigerant composition as claimed in any one of claims 2 to 7 , characterised in that it comprises from 50 to 70 Z by weight of difluoromethyl trifluoromethyl ether and from 50 to 30 Z by weight of difluoromethane. 9. A refrigerant composition as claimed in claim 2 or claim 3, characterised in that it comprises from 25 to * - 99 Z by weight of difluoromethyl trifluoromethyl ether and from 75 to 1 Z by weight of difluoromethane. 10. A refrigerant composition as claimed in claim 9, characterised in that it comprises from 50 to 99 Z by weight of difluoromethyl trifluoromethyl ether and frpm 10 50 to 1 Z by weight of difluoromethane. 11. A refrigerant composition as claimed in claim 9 or claim 10, characterised in that it comprises from 70 to 90 Z by weight of difluoromethyl trifluoromethyl ether and from 30 to 10 Z by weight of difluoromethane. 12. A refrigerant composition as claimed in any one of 15 claims 9, 10 or 11, characterised in that it comprises from 75 to 90 Z by weight of difluoromethyl trifluoromethyl ether and from 25 to 10 Z by weight of difluoromethane. 13. A refrigerant composition as claimed in claim 1 20 which additionally comprises at least one other refrigerant compound having a low or zero ozone depletion potential selected from other hydrofluoroalkanes and other fluorinated ethers containing residual hydrogen atoms. 25 14. A heat transfer device containing a refrigerant composition as claimed in any one of claims 1 to 13. 15. Use of a refrigerant composition as claimed in any one of claims 1 to 13 in a heat transfer device. 16. A method for providing cooling which comprises 3 condensing the refrigerant composition claimed in any one of claims 1 to 13 and thereafter evaporating it in 1 a heat exchange relationship with a body to be cooled. 17. A method for providing heating which comprises condensing the refrigerant composition claimed in any 35 one of claims 1 to 13 in a heat exchange relationship with a body to be heated and thereafter evaporating it

Inventors: MORRISON JAMES DAVID, POWELL RICHARD LLEWELLYN, MORRISON, JAMES, DAVID, POWELL, RICHARD, LLEWELLYN
Applicants: ICI PLC, IMPERIAL CHEMICAL INDUSTRIES PLC
Application year: 1992
Main classification: C09K5
IPC codes: C07C19, C07C43, C09K5, F25B1