NON-AZEOTROPIC REFRIGERANT MIXTURE OF R23, R125 AND R32

Abstract: A non-azeotropic refrigerant mixture is provided for use in heat pumps which provides improved efficiency, in terms of coefficient of performance and compressor power, than available refrigerants or mixtures thereof. The refrigerant is a ternary mixture of 1 % to 10 % R23 (trifluoromethane), 1 % to 70 % R125 (pentafluoroethane), with the balance being R32 (methylene fluoride; difluoromethane). The mixture can be used in heat pumps and other machines designed for R22 and/or R502 without modification, and is environmentally acceptable.

Description: NON-AZEOTROPIC REFRIGERANT MIXTURE OF R23. R125 AND R32 1. Technical Field; This invention relates to a non-azeotropic refrigerant mixture, suitable as a working fluid for heat pump applications as well as in other vapour compression machines. By use of this mixture, the cooling and heating efficiencies of heat pumps can be significantly improved. The mixture is entirely compatible with R22 and R502 refrigerants currently used in heat pumps, and so does not require changes in the design of such heat pumps. R22 is chlorodifluoromethane (CHCLF 2 ) and R502 is a mixture of R22 and R115 which is chloropentafluoroethane (CHC1F 2 CHF3). However, other vapour compression equipment can use the mixture as a drop-in replacement for presently used refrigerants, depending on the mixture composition. In addition, with these compositions, the mixture is environmentally acceptable. 2. Background Art: a) General The theπnodynamic performance of an energy conversion device may be improved by using a non-azeotropic mixture iir a vapour cycle. A non- azeotropic mixture has a temperature distribution parallel to * that of the surrounding fluid with which heat transfer takes place during the evaporation and condensation processes which are part of the cycle. Interest has increased in recent years in the use of non-azeotropic refrigerant mixtures (NARM) to improve the performance of energy conversion devices, b) Prior Art Various NARM have been proposed or used in the past. Usually, these have two components, but some having three (i.e. ternary mixtures) have been proposed, for example in: U.S. Patent No. 4,344,292 (Rojey) - issued August 17, 1982 U.S. Patent No. 4,680,939 (Rojey) - issued July 21, 1987 U.S. Patent No. 4,810,403 (Bivens) - issued March 7, 1989 U.S. Patent No. 4,812,250 (A brosino et al.) - issued March 14, 1989 U.S. Patent No. 4,978,467 (Shankland) - issued December 18, 1990 U.S. Patent No. 5,049,296 (Gu) - issued September 17, 1991 U.S. Patent No. 5,053,155 (Maher) - issued October 1, 1991 U.S. Patent No. 5,059,338 (Yoshida) - issued October 22, 1991 European Patent Application No. 419,042 (Pearson) - published March 27, 1991 European Patent Application No. 451,692 (Omure et al.) .- published October 16, 1991 European Patent Application No. 430,169 (Yoshida et al.) - published June 5, 1991 European Patent Application No. 430,171 (Yoshida et al.) - published June 5, 1991 In our co-pending PCT Application Serial No. PCT/CA92/00208, filed May 15, 1992, there is described a ternary non-azeotropic mixture of 4% to 10% trifluoromethane (R23), 4% to 30% of 1, l-difluoroethane (R152a) with the balance of chlorodifluoromethane (R22). This may have improved properties compared to pure R22, and is more environmentally acceptable than R22 since the amount of chlorine in the refrigerant is reduced, being only present in the R22. However, recently published information suggests that R22 may have more negative impact on the ozone layer and the greenhouse effect than previously estimated. ' - The present invention provides a ternary non-azeotropic mixture which has similar advantages over R22 as does the mixture of PCT Serial No. PCT/CA92/00208 but in which no chlorinated compounds are used; instead the mixture contains only hydrofluorocarbons (HFC's), such as pentafluoroethane (R.125) and methylene fluoride (R32), also known as difluoromethane. Since the mixture of this invention contains no chlorine it is environmentally safe. R125 has a molecular weight of 120.02 and boils at -48.50°C; it is non-flammable. R32 has a molecular weight of 79.20 and boils at -51.61°C and is non-flammable at concentrations not higher than 65% in a mixture. The third component, R23, has a molecular weight of 70.02 and boils at -82.06°C and is non-flammable. 3. Disclosure of Invention: The present invention provides a unique non-azeotropic refrigerant mixture containing R23, R125, and R32 refrigerants which has a remarkably good coefficient of performance without sacrificing either thermal capacity or environmentally desirable properties. In accordance with one aspect of the present invention, a refrigerant for use in a heat pump or other equipment designed for R22 or R502, without modification of the equipment, comprises a ternary non-azeotropic mixture of known refrigerants, as follows: R23 (CHF 3 ; trifluoromethane) 1% to 20% R125 (CHF 2 CF 3 ; pentafluoroethane) 1% to 70% R32 (CH 2 F 2 ; methylene fluoride or difluoromethane) Balance All references to percentage composition given herein are by weight. The precise composition of the mixture will vary with particular working conditions; however the mixtures will all be within this broad range to avoid degraded performance, high condenser operating pressures which are incompatible with existing equipment, and flammability of the mixture. The following are examples of preferred ranges and compositions. Composition (a) Composition (b) Composition (c) 4. Brief Description of the Drawings Reference will be made to the following drawings for a better understanding of non-azeotropic mixtures and the particular mixtures of this invention, i.e.: Fig. 1 are graphs showing how coefficient of performance for refrigeration changes with temperature for pure refrigerant R22; R502 which is a mixture of R22 and R115 having a boiling point of -45.44°C and molecular weight 111.63; and mixtures in accordance with the invention; Figs. 2 through 6 show graphs of performance characteristics vs temperature at the inlet to the liquid evaporator, for the different refrigerant compositions shown above; Figs. 7 and 8 show how the coefficient of performance of a.heat pump varies with volumetric cooling capacity for different refrigerants; Fig. 9 shows a graph of pressure against temperature for different refrigerants; Figs. 10 and 11 show graphs of the volumetric capacity for heating and cooling respectively, against temperature, both for Applicant's mixture and mixtures of other HFC's; and Fig. 12 shows a graph of pressure against temperature for the same mixtures as Figs. 10 and 11. 5. Detailed Description: a) The Behaviour of a Non-Azeotropic Mixture An azeotropic mixture of two substances or more cannot be separated into its components by distillation. Such a mixture evaporates and condenses as a single substance with properties that are different from those of either constituent. Whereas pure substances or azeotropic mixtures have a constant phase changing temperature (e.g. boiling point) at a given pressure, a non- azeotropic mixture condenses and boils over a temperature range by an isobaric heating process. b) Desirable Properties in Non-Azeotropic Refrigerant Mixtures are as follows: Thermodynamic Properties 1. Low condensing pressure 2. Low boiling temperature 3. Low freezing temperature 4. High latent heat of vaporization 5. Proper P-x-T relationship 6. Low vapour and liquid specific volumes 7. Low specific heat of liquid 8. Low specific heat of vapour Physical Properties 1. High thermal conductivity of vapour 2. Low viscosity 3. Low molecular weight 4. High equilibrium mixing and solubility 5. Solubility with water 6. Solubility with lubricating oil 7. Stability Chemical Properties 1. Low degrading aspects (i.e. low Greenhouse Depletion Potential) 2. Low ozone compatibility (i.e. low Ozone Depletion Potential) Safety Properties 1. Non-flammable and non-explosive 2. Non-toxic 3. Weak odour Economic Properties 1. Low cost and ready availability 2. High overall heat transfer coefficient Specific Properties 1. Highly non-azeotropic combination 2. High coefficient of performance (COP) 3. Low volumetric cooling capacity c) Thermodynamic Properties of Mixture The Carnhan-Starling-DeSantis (CDS) equation of state has been employed to calculate the thermodynamic properties of the proposed non- azeotropic mixtures in the different phases. Tables 1, 2 and 3 give the thermodynamic properties including temperatures during evaporation and condensation at various pressures. The Tables are for the following preferred compositions (see above): R-23 R-125 R-32 Table 1 - Composition (a) 5% 30% 65% Table 2 - Composition (b) 5% 40% 55% Table 3 - Composition (c) 5% 70% 25% Fig. 9 shows that the proposed compositions behave as a homogenous refrigerant over the investigated range having pressure/temperature characteristics similar to R22 and R502. This is a significant characteristic, since handling and packaging expose the refrigerant to various temperatures. The similarity to R22 and R502 means that standard equipment which uses R22 or R502 can utilize this mixture without modification. d) Environmental Properties With the concentration of R32 (methylene fluoride or difluoromethane) in the mixture not higher than about 65% by weight, the proposed non-azeotropic mixture is non-flammable. The proposed mixture is an environmentally friendly refrigerant because of the following characteristics: - Mixture components R23, R32 and R125 each have zero Ozone Depletion Potential (ODP). The three components R23, R32 and R125 also have very low Greenhouse Depletion Potential (GDP) of less than 0.1. e) Comparison with Other Refrigerants: Performance of Mixture ' , The mixtures of the said refrigerants as described herein has been found to result in very desirable mixtures in attaining low evaporating temperatures and a reasonable head pressure and can be used with conventional heat pumps or other machines designed for R22 and/or R502 without the requirement for any major modifications or change in equipment. The performance of an air/air heat pump using the mixture has been assessed by experiments. This heat pump comprises an air/refrigerant evaporator into which the mixture is introduced and from which it is discharged to a hermetic compressor for compressing the vapour mixture into an air finned condenser. After condensation, the mixture is discharged to an expansion valve; it is finally expanded through the expansion valve and recycled to the evaporator. Evaluations of performance have been made with the refrigerant mixtures using air temperatures at the evaporator from -30°C to 5°C at constant air temperature of 27°C at the inlet to the air condenser. The series of results illustrated in Figs. 1 to 6 show the experimental results obtained with pure R22, then with pure R502, and then with mixtures or R23 R125/R32 at composition percentages of 5/30/65; 5/40/55; and 5/70/25. These results indicate a higher performance than with R22 and R502; this performance can be significantly improved with more careful choice of the composition ratios to suit particular temperature applications. Samples of further performance results, obtained at entering air temperature to the evaporator from -30°C to 5°C and air entering temperature to the condenser of 35°C are displayed in Figs. 7 and 8. The coefficient of performance (COPR) shown in Figs. 1 through 8 is defined as the ratio of the heat powder delivered by the heat pump to the electric power consumed by the motor which drives the compressor. Fig. 9 shows the proposed mixture of the present invention, containing R23/R125/R32; which in the high temperature range has properties higher than that of pure R22. However, these proposed concentrations can be employed in equipment designed for R22, since their head pressure is below the equipment design pressure. Figs. 10 through 12 show a comparison between -a mixture of R23/R125/R32 at 10%/30%/60% composition, in accordance with this invention (shown at (1) on the graph), and mixtures derived from the above-mentioned European Patent Application No. 451,692 of Omure et al. This latter patent application discloses various mixtures of HFC's, but for purposes of comparison mixtures of R134a/R125/R32 and R143a/R125/R32 at 10%/30%/60% were chosen. Fig. 10 shows volumetric capacity in heating, Fig. 11 shows volumetric capacity in cooling, and Fig. 12 shows pressure/temperature characteristics. It is notable that in Figs. 10 and 11 the volumetric capacity of the inventive mixture, which is an important measure of the efficiency of a refrigerant, is superior to those of Omure at al. Furthermore, it may be noted that Omure et al. proposes compositions intended as replacements for Rll and R12, not R22 or R502. 8 TABLE 1 - COMPOSITION a) SATURATION PROPERTIES FOR R23 /R125/ R32 MIXING COEFFICIENTS): 0.000 0.000 0.000 COMPOSITION: 0.050 I1ASS FRACTION = 0.058 MOLE FRACTION R23 0.300 I1ASS FRACTION = 0.298 MOLE FRACTION R125 ' 0.050 MASS FRACTION * 0.6 * 15 MOLE FRACTION R32 PRESSURE TEMPERATURE DENSITY ENTHALPY ENTROPY LIQ VAP LIQ VAP LIQ EVAP VAP LIQ VAP CkPa) (C) (KG/M**3) CKJ/KG) tKJ/K8* ) 34.474 -76.310 -73.654 4485.803 4.870 -9.908 87.389 77.481 -0.022 0.148 68.948 -64.228 -61.677 4366.787 9.277 -5.437 85.227 79.790 0.000 0.404 103.422 -56.369 -53.885 4288.055 13.534 -2.461 83.723 81.262 0.014 0.397 137.896 -50.388 -47.955 4227.177 17.706 -0.158 82.517 82.359 0.024 0.392 206.844 -41.323 -38.965 4132.902 25.899 3.402 80.569 83.971 0.040 0.385 275.792 -34.393 -32.094 4058.855 33.979 6.183 78.969 85.642 0.052 0.380 310.266 -31.426 -29.152 4026.545 37.996 7.390 78.252 86.081 0.052 0.378 344.740 -28.454 -26.454 3996.556 42.003 8.506 77.575 86.843 0.061 0.377 379.214 -26.187 -23.958 3968.485 46.004 9.546 76.933 86.479 0.065 0.375 413.688 -23.840 -21.632 3942.026 50.002 10.523 76.319 86.843 0.069 0.374 448.162 -21.639 -19.450 3916.943 53.999 11.446 75.730 87.186 0.073 0.372 482.636 -19.565 -17.394 3893.050 57.997 12.321 75.162 87.484 0.076 0.371 517.110 -17.601 -15.448 3870.197 61.998 13.155 74.613 87.768 0.080 0.370 551.584 -15.736 -13.599 3848.261 66.003 13.952 74.081 88.033 0.083 0.369 586.058 -13.957 -11.837 3827.141 70.013 14.716 73.564 88.280 0.086 0.368 620.532 -12.257 -10.152 3806.751 74.030 15.451 73.060 88.511 0.088 0.367 655.006 -10.627 -8.537 3787.018 78.055 16.159 72.568 88.727 0.091 0.366 689.480 -9.062 -6.986 3767.881 82.088 16.843 72.087 88.930 0.094 0.365 723.954 -7.554 -5.493 3749.286 86.131 17.505 71.616 89.121 0.096 0.364 758.428 -6.101 -4.053 3731.186 90.183 18.147 71.154 89.301 0.099 0.364 792.902 -4.697 -2.663 3713.541 94.247 18.770 70.700 89.470 0.101 0.363 827.376 -3.338 -1.317 3696.314 98.332 19.376 70.254 89.631 0.103 0.362 861.850 -2.021 -0.013 3679.474 102.408 19.966 69.816 89.782 0.105 0.361 896.324 -0.744 1.251 3662.993 106.508 20.541 69.384 89.925 0.107 0.361 930.798 0.496 2.479 3646.844 110.620 21.102 6B.95B 90.060 0.109 0.360 965.272 1.703 3.674 3631.005 114.746 21.650 68.538 90.188 0.111 0.360 999.746 2.877 4.836 3615.456 118.886 22.187 68.123 90.310 0.113 0.359 1034.22 4.021 5.969 3600.177 123.041 22.711 67.714 90.425 0.115 0.358 1068.694 5.137 7.073 3585.152 127.211 23.225 67.309 90.534 0.117 0.358 1103.168 6.226 8.150 3570.365 131.396 23.729 66.908 90.637 0.119 0.357 1137.642 7.290 9.203 3555.802 135.596 24.223 66.512 90.735 0.120 0.357 1172.116 8.330 10.232 3541.450 139.814 24.709 66.120 90.828 0.122 0.356 1206.590 9.347 11.238 3527.297 144.047 25.185 65.731 90.916 0.124 0.355 1241.064 10.342 12.222 3513.332 148.298 25.654 65.346 91.000 0.125 0.355 1275.538 11.317 13.187 3499.544 152.566 26.115 64.964 91.078 0.127 0.354 1310.012 12.273 14.131 3485.924 156.852 26.566 64.585 91.153 0.128 0.354 1344.486 13.209 15.058 3472.464 161.156 27.015 64.209 91.224 0.130 0.353 1378.960 14.128 15.996 3459.154 165.478 27.454 63.838 91.290 0.131 0.353 1413.434 15.030 16.858 3445.987 169.819 27.8B8 63.465 91.353 0.133 0.352 1447.908 15.916 17.733 3432.957 174.179 28.315 63.097 91.412 0.134 0.352 1482.382 16.786 18.593 3420.056 178.559 28.737 62.732 91.468 0.136 0.351 1516.856 17.641 19.438 3407.277 182.959 29.153 62.368 91.521 0.137 0.351 1551.330 18.482 20.269 3394.616 187.378 29.563 62.007 91.570 0.139 0.350 1585.804 19.309 21.086 3382.066 191.818 29.969 61.647 91.616 0.140 0.350 1620.278 20.122 21.890 3369.622 196.280 30.369 61.290 91.659 0.141 0.350 1654.752 20.923 22.681 3357.279 200.762 30.765 60.934 91.700 0.143 0.349 1689.226 21.711 23.459 3345.032 205.266 31.157 60.581 91.737 0.144 0.349 1723.700 22.488 24.226 3332.878 209.791 31.543 60.22B 91.772 0.145 0.348 1758.174 23.253 24.982 3320.810 214.339 31.926 59.877 91.804 0.146 0.348 1792.648 24.007 25.726 3308.826 218.910 32.926 59.528 91.833 0.148 0.347 1827.122 24.751 26.460 3296.922 223.503 32.680 59.180 91.860 0.149 0.347 1861.596 25.484 27.184 3285.094 228.120 33.051 58.834 91.885 0.150 0.346 1896.070 26.207 27.897 3273.338 232.760 33.418 58.488 91.907 0.151 0.346 1930.544 26.920 28.601 3261.651 237.424 33.782 58.144 91.926 0.152 0.346 1965.010 27.624 29.296 3250.030 242.113 34.143 57.801 91.944 0.154 0.345 1999.492 28.319 29.981 3238.471 246.026 34.501 57.450 91.959 0.155 0.345 2033.966 29.005 30.658 3226.972 251.565 34.855 57.117 91.972 0.156 0.344 2068.440 29.682 31.326 3215.531 256.329 35.206 56.777 91.983 0.157 0.344 3/18110 TABLE 1 - COMPOSITION a) - Continued NOTE: ALL LIQUID PROPERTIES EVALUATED AT THE BUBBLE POINT TEMPERATURE (TLIQ) ALL VAPOUR PROPERTIES EVALUATED AT THE DEW POINT TEMPERATURE (TVAP) TABLE 2 - COMPOSITION b) SATURATION PROPERTIES FOR R23 /R125 /R32 / MIXING COEFFICIENT ' S): 0.000 0.000 0.000 COMPOSITION: 0.050 MASS FRACTION = 0.058 MOLE FRACTION R23 0.400 MASS FRACTION = 0.397 MOLE FRACTION R125 O.550 MASS FRACTION = 0.545 MOLE FRACTION R32 SUBSTITUTESHEET TABLE 2 - COMPOSITION b) - Continued NOTE: ALL LIQUID PROPERTIES EVALUATED AT THE BUBBLE POINT TEMPEARTURE (TLIQ) ALL VAPOUR PROPERTIES EVALUATED AT THE DEW POINT TEMPERATURE (TVAP) SUBSTITUTE SHEET TABLE 3 - COMPOSITION c) SATURATION PROPERTIES FOR R23 /R125 /R32 / SUBSTITUTE SHEET /18110 13 TABLE 3 - COMPOSITION c) - Continued PRESSURE TEMPERATURE CV CP LIQ VAP LIQ VAP LIQ VAP (KPA) (C) KJ/KG*K KJ/KG*K 5.000 -75.376 -71.626 0.382 0.240 0.438 0.278 10.000 -63.053 -59.415 0.394 0.250 0.453 0.290 15.000 -55.024 -51.465 0.402 0.256 0.463 0.298 20.000 -48.906 -45.411 0.408 0.261 0.471 0.304 30.000 -39.622 -36.232 0.417 0.268 0.463 0.315 40.000 -32.517 -29.212 0.424 0.274 0.494 0.324 45.000 -29.472 -26.206 0.427 0.276 0.498 0.328 50.000 -26.679 -23.450 0.429 0.279 0.503 0.332 55.000 -24.094 -20.898 0.431 0.281 0.507 0.335 60.000 -21.683 -18.521 0.434 0.283 0.511 0.339 65.000 -19.421 -16.291 0.436 0.285 0.515 0.343 70.000 -17.289 -14.169 0.437 0.286 0.518 0.346 75.000 -15.271 -12.200 0.439 0.288 0.522 0.350 80.000 -13.352 -10.310 0.441 0.290 0.525 0.353 65.000 -11.523 -8.508 0.442 0.291 0.529 0.357 90.000 -9.774 -6.786 0.444 0.293 0.532 0.360 95.000 -8.097 -5.136 0.445 0.294 0.535 0.363 100.000 -6.486 -3.550 0.446 0.296 0.539 0.367 105.000 -4.934 -2.024 0.447 0.297 0.542 0.370 110.000 -3.438 -0.552 0.449 0.299 0.545 0.373 115.000 -1.992 0.870 0.450 0.300 0.548 0.377 120.000 -0.593 2.246 0.451 0.301 0.551 0.380 125.000 0.763 3.579 0.452 0.303 0.555 0.383 130.000 2.079 4.672 0.453 0.304 0.588 0.387 135.000 3.357 6.127 0.454 0.305 0.561 0.390 140.000 4.600 7.348 0.454 0.306 0.564 0.393 145.000 5.811 8.537 0.455 0.308 0.567 0.397 150.000 6.990 9.695 0.456 0.309 0.570 0.400 155.000 8.140 10.824 0.457 0.310 0.573 0.404 160.000 9.263 11.925 0.458 0.311 0.576 0.407 165.000 10.360 13.001 0.458 0.312 0.579 0.411 170.000 11.432 14.432 0.459 0.313 0.583 0.414 175.000 12.481 15.082 0.460 0.314 0.586 0.448 180.000 13.508 16.088 0.460 0.315 0.589 0.422 185.000 14.514 17.074 0.461 0.316 0.592 0.425 190.000 15.499 18.040 0.462 0.318 0.595 0.429 195.000 16.466 18.987 0.462 0.319 0.599 0.433 200.000 17.414 19.916 0.463 0.320 0.602 0.437 205.000 18.345 20.827 0.463 0.321 0.605 0.440 210.000 19.259 21.722 0.464 0.322 0.609 0.444 215.000 20.157 22.602 0.464 0.323 0.612 0.448 220.000 21.040 23.465 0.465 0.324 0.615 0.452 225.000 21.908 24.315 0.465 0.325 0.619 0.457 230.000 22.762 25.150 0.466 0.326 0.623 0.461 235.000 23.602 25.971 0.466 0.327 0.626 0.465 240.000 24.429 26.780 0.467 0.328 0.630 0.469 245.000 25.244 27.576 0.467 0.329 0.633 0.474 250.000 26.046 28.360 0.467 0.329 0.637 0.478 255.000 26.836 29.132 0.466 0.330 0.641 0.483 260.000 27.615 29.893 0.466 0.331 0.645 0.487 265.000 28.384 30.643 0.468 0.332 0.649 0.492 270.000 29.141 31.383 0.469 0.333 0.653 0.497 275.000 29.868 32.112 0.469 0.334 0.657 0.502 280.000 30.626 32.832 0.469 0.335 0.611 0.507 285.000 31.354 33.542 0.470 0.336 0.665 0.512 290.000 32.072 34.243 0.470 0.337 0.670 0.517 295.000 32.781 34.934 0.470 0.336 0.674 0.522 300.000 33.482 35.617 0.470 0.339 0.679 0.527 NOTE: ALL LIQUID PROPERTIES EVALUATED AT THE BUBBLE POINT TEMPERATURE (TLIQ) ALL VAPOUR PROPERTIES EVALUATED AT THE DEU POINT TEMPEARTURE (TVAP)

Claims: CLAIMS; 1. A non-azeotropic refrigerant mixture, capable of being used in equipment designed for R22 or R502 without modification of said equipment, characterized in that it is a ternary mixture consisting essentially of: trifluoromethane (R23) 1% to 20% pentafluoroethane (R125) 1% to 70% difluoromethane (methylene fluoride; R32) Balance 2. A non-azeotropic refrigerant mixture according to claim 1, consisting essentially of: R23 1% to 10% R125 1% to 70% R32 Balance 3. A non-azeotropic refrigerant mixture according to claim 1, consisting essentially of: R23 2% to 20% R125 2% to 50% R23 Balance ' - 4. A non-azeotropic refrigerant mixture according to claim 1, consisting essentially of: R23 2% to 10% R125 10% to 40% R32 Balance 5. A non-azeotropic refrigerant mixture consisting essentially of: R23 3% to 10% R125 30% to 50% R32 Balance " 6. A heat transfer process using a heat pump, and wherein a refrigerant is successively evaporated while extracting heat from a heat source and condensed while giving heat to receiving fluid, wherein the refrigerant is a non- azeotropic ternary mixture, capable of being used in a heat pump designed for R22 or R502 without modification of the heat pump, characterized in that said mixture consists essentially of : trifluoromethane (R23) 1% to 20% pentafluoroethane (R125) 1% to 70% difluoromethane (methylene fluoride; R32) Balance 7. A heat transfer process according to claim 6, wherein said refrigerant mixture consists essentially of: R23 1% to 10% R125 1% to 70% R23 Balance 8. A heat transfer process according to claim 6, wherein said refrigerant mixture consists essentially of: R23 2% to 20% R125 2% to 50% R32 Balance A heat pump characterized by having a refrigerant as claimed in claim 1. 10. A heat pump characterized by having a refrigerant as claimed in claim 2. 11. A heat pump characterized by having a refrigerant as claimed in claim 3. 12. A heat pump characterized by having a refrigerant as claimed in claim 4. SUBSTITUTE SHEET

Inventors: SAMI SAMUEL, SAMI, SAMUEL
Applicants: UNIV MONCTON, UNIVERSITY OF MONCTON
Application year: 1993
Main classification: C09K5
IPC codes: C09K5