NEAR-AZEOTROPIC BLENDS FOR USE AS REFRIGERANTS

Abstract: Near-Azeotropic blends of: pentafluoroethane and 1,1,1-trifluoroethane with one or more of chlorodifluoromethane, 1,2,2,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, 1-chloro-1,1,2,2-tetrafluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, 1,1,1,2,2,3,3-heptafluoropropane, and perfluorocyclopropane; chlorodifluoromethane and pentafluoroethane with one or more of ethane, butane, isobutane, dimethyl ether, propylene, and difluoromethane; chlorodifluoromethane with 1,1,1-trifluoroethane and 1,2,2,2-tetrafluoroethane, propane and pentafluoroethane, or 1,1,1-trifluoroethane and octafluoropropane; and pentafluoroethane with fluoroethane and 1,2,2,2-tetrafluoroethane, along with their use as refrigerants.

Description: TITLE NEAR-AZEOTROPIC BLENDS FOR USE AS REFRIGERANTS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of pending U.S. Patent Application No. 07/558,346 filed July 26, 1990. BACKGROUND OF THE INVENTION The present invention relates to ternary and higher blends of fluorinated hydrocarbons and more specifically to near-azeotrope constant-boiling blends and expands upon refrigerant compositions for cooling and heating applications, as heretofore described in U.S. Patent No. 4,810,403. Such blends are useful as refrigerants, heat transfer media, gaseous dielectrics, expansion agents, aerosol propellants and power cycle working fluids. Concern over the ozone depletion potential of certain halocarbons has resulted in a search for alternative compounds having lower ozone depletion potentials. A present day commercial binary azeotrope refrigerant widely used in supermarket refrigerators consists of 48.8 wt% chlorodifluoromethane (HCFC-22) and 51.2 wt% chloropentafluoroethane (CFC-115) and is generally referred to as Refrigerant-502. Due to the presence of chlorine in CFC-115, CC1F2CF3, is expected to be subject to reduced usage because of its high ozone depletion potential. Additionally chlorine containing medium to low temperature refrigerants which may be subject to reduced usage could be replaced with all HFC containing blends described within. In refrigeration applications, refrigerant is often lost through leaks during operation, such as through shaft seals, hose connections, solder joints, and broken lines. In addition, refrigerant may be released to the atmosphere during maintenance procedures performed on refrigeration equipment. Most commercial refrigerants which are now used are pure fluids or azeotropes, many of these refrigerants have ozone depletion potentials when released to the atmosphere. Some nonazeotropic blends of refrigerants may also be used but they have the disadvantage of changing composition when a portion of the refrigerant charge is leaked or discharged to the atmosphere. Should these blends contain a flammable component, they could also become flammable due to the change of composition which occurs during the leakage of vapor from refrigeration equipment. Refrigeration equipment operation could also be adversely affected due to this change in composition and vapor pressure which results from fractionation. What is needed, therefore, are substitute refrigerants which maintain important refrigerant properties of vapor pressure and nonflammability over a wide range of compositions, while also having reduced ozone depletion potential. SUMMARY OF THE INVENTION According to the present invention, near-azeotrope constant-boiling blends have been discovered comprising effective amounts of pentafluoroethane (HFC-125) and 1,1,1-trifluoroethane (HFC-143a) with one or more of the compounds set forth in Table I: TAPfrE I Generally Chemical Name Accepted Nomenclatur chlorodifluoromethane HCFC-22 1,2,2,2-tetrafluoroethane HFC-134a 1,1,2,2-tetrafluoroethane HFC-134 1-chloro-l,1,2,2-tetrafluoroethane HFC-124a 1-chloro-l,2,2,2-tetrafluoroethane HFC-124 1,1,1,2,3,3,3-heptafluoropropane HFC-227ea 1,1,1,2,2,3,3-heptafluoropropane HFC-227ca perfluorocyclopropane FC-C216 The near-azeotrope constant-boiling compositions are blends of HFC-125 and HFC-143a with any one of HCFC-22, HFC-134a, HFC-134, HFC-124a, HFC-124, HFC-227ea, HFC-227ca, and FC-C216 or mixture thereof as set forth below. The compositions are chosen such that the blends have vapor pressures substantially equal to the vapor pressure of Refrigerant-502 and other medium to low temperature refrigerants, over a temperature range as encountered in their use as refrigerants such as -50 to 100 degrees Celcius. The compositions have ozone depletion potentials (ODP) and global warming potentials (GWP) of 0 to 0.02 and 0.5 to 1.0 respectively which are substantially lower than the Refrigerant-502 value of 0.25 ODP and 5.1 GWP. Additional, near-azeotrope constant-boiling blends have been discovered comprising effective amounts of chlorodifluoromethane (HCFC-22) and/or pentafluoroethane (HFC-125) with one or more of the compounds set forth in Tables I and II: The near-azeotrope constant-boiling compositions are blends of HCFC-22 with propane and HFC-125, HCFC-22 with HFC-143a and HFC-134a, or HCFC-22 with HFC-143a and FC-218. Also, a near-azeotrope constant-boiling composition is a bl of HFC-125 with HFC-161 and HFC-134a. The compositions are chosen such that the blends have vapor pressures substantially equal to the vapor pressure of Refrigerant-502 and other medium to low temperature refrigerants, over a temperature range a encountered in their use as refrigerants such as -50 to 100 degrees Celcius. The compositions have ozone depletion potentials (ODP) lower than Refrigerant-50 however, blends formulated with octafluoropropane ma have global warming potentials lower, or equal to Refrigerant-502 depending on the composition of octafluoropropane. The near-azeotropic blends may also be use to produce heat by condensing the composition in the vicinity of the body to be heated and thereafter evaporating the condensate. The use of near-azeotropic blends minimize the problem of component fractionation and handling system operations. Finally, the near-azeotropic blends can be formulated to offer the same advantage as Refrigerant-502 and other medium to low temperature refrigerants as being nonflammable at room temperatu and atmospheric pressure. DETAILED DESCRIPTION OF THE INVENTION By refrigeration is meant the utilization o physical change in a substance to produce a cooling o heating effect. The physical change can be, for example, a change from the solid state to the liquid state or a change from the liquid state to the vapor state or the reverse order. By refrigerant is meant the substance which undergoes physical change in refrigeration. By ozone depletion potential is meant the ratio of the calculated ozone depletion in the stratosphere resulting from the emission of a compoun compared to the ozone depletion potential resulting from the same rate of emission of CFC-11 which is set at 1.0. A method of calculating ozone depletion potential is described in "The Relative Efficiency of a Number of Halocarbons for Destroying Stratospheric Ozone*, by D. J. Wuebbles, Lawrence Liver ore Laboratory report UCID-18924, January, 1981, and "Chlorocarbon Emission Scenarios: Potential Impact on Stratospheric Ozone*, by D. J. Wuebbles, Journal Geophysics Research, 88, 1433-1443, 1983. By nonflammable is meant a gas mixture in air which will not burn when subjected to a spark igniter as described in "Limits of Flammability of Gases and Vapours", Bulletin 503, H.F. Coward et al., Washington, U.S. Bureau of Mines, 1952. By "vapor pressures substantially equal to the vapor pressure of Refrigerant-502 and other mediu to low temperature refrigerants" is meant a vapor pressure which is plus or minus twenty-five percent o the vapor pressure of Refrigerant-502 and other mediu to low temperature refrigerants at the same temperature within the range of -50 to 100 degrees Celsius. By substantially lower ozone depletion potential than the ozone depletion of Refrigerant-5 is meant an ozone depletion potential at least fift percent less than the ozone depletion potential of Refrigerant-502, i.e. less than 0.125. By substantially lower global warming potential than the global warming potential of Refrigerant-502 is meant a global warming potential least fifty percent less than the global warming potential of Refrigerant-502, i.e., less than 2.55. As mentioned above, when a refrigerant bl contains a flammable component, the possibility of either the discharged vapor or the remaining refrigerant upon leakage becoming flammable constitutes a highly undesirable safety hazard. Th present compositions can be so formulated that the lowest boiling and highest boiling components are nonflammable so that even when the intermediate boiling component is flammable, not only is the original composition nonflammable, but additionally, neither the leaking vapor nor the remaining refrigerant becomes flammable. The present invention provides near-azeotropic blends which have vapor pressures ne that of Refrigerant-502 and other medium to low temperature refrigerants and surprisingly even afte an 80 percent evaporation loss by weight. A vapor pressure/temperature relation similar to that of Refrigerant-502 and other medium to low temperature refrigerants is particularly desirable since much existing refrigeration equipment which has been designed to use Refrigerant-502 and other medium to low temperature refrigerants can also use the refrigerants of the present invention with little or no modification. The preferred halocarbon components in the blends are listed in the Table III: The blends of the instant invention compris HCFC-22 and/or HFC-125 with one or more of the others from Table III. The near-azeotropic blends of the instant invention can be prepared by any convenient method including mixing or combining the desired component amounts. A preferred method is to weigh the desired component amounts and thereafter combine them in an appropriate container. The near-azeotropic blends of the present invention have the following compositions: 35 to 65, preferably 50 to 60, and most preferably 55.0 weight percent HFC-125; 30 to 60 preferably 35 to 45, and most preferably 40.0 weight percent HFC-l43a; and 3 to 15, preferabl 3 to 10, and most preferably 5.0 weight percent HFC-134a. 35 to 65, preferably 50 to 60, and most 5 preferably 55.0 weight percent HFC-125; 30 to 6 preferably 35 to 45, and most preferably 40.0 weight percent HFC-143a; and 3 to 15, preferabl 3 to 10, and most preferably 5.0 weight percent HFC-134. 10 - 35 to 65, preferably 50 to 60, and most preferably 55.0 weight percent HFC-125; 30 to 6 preferably 35 to 45, and most preferably 40.0 weight percent HFC-143a; and 3 to 15, preferabl 3 to 10, and most preferably 5.0 weight percent 15 HFC-124a. 35 to 65, preferably 50 to 60, and most preferably 55.0 weight percent HFC-125; 30 to 6 preferably 35 to 45, and most preferably 40.0 weight percent HFC-143a; and 3 to 15, preferabl 20 3 to 10, and most preferably 5.0 weight percent HFC-124. 35 to 65, preferably 50 to 60, and most preferably 55.0 weight percent HFC-125; 30 to 6 preferably 35 to 45, and most preferably 40.0 25 weight percent HFC-143a; and 3 to 15, preferabl 3 to 10, and most preferably 5.0 weight percent HFC-227ea. 35 to 65, preferably 50 to 60, and most preferably 55.0 weight percent HFC-125; 30 to 6 30 preferably 35 to 45, and most preferably 40.0 weight percent HFC-143a; and 3 to 15, preferabl 3 to 10, and most preferably 5.0 weight percent HFC-227ca. 35 to 65, preferably 50 to 60, and most 35 preferably 55.0 weight percent HFC-125; 30 to 6 preferably 35 to 45, and most preferably 40.0 weight percent HFC-143a; and 3 to 15, preferably 3 to 10, and most preferably 5.0 weight percent FC-C216. - 5 to 30, preferably 15 to 25, and most preferabl 20.0 weight percent HFC-125; 30 to 60, preferabl 30 to 40, and most preferably 35.0 weight percen HFC-143a; and 30 to 55, preferably 40 to 50, and most preferably 45.0 weight percent HCFC-22. - 30 to 55, preferably 40 to 50, and most preferably 45.0 weight percent HCFC-22; 30 to 60 preferably 45 to 55, and most preferably 50.0 weight percent HFC-143a; and 3 to 15, preferably 3 to 10, and most preferably 5.0 weight percent HFC-134a. 1 to 98.9, preferably 30 to 85, and most preferably 45 to 65 weight percent HCFC-22; 0.1 to 15, preferably 1 to 10, and most preferably 2 to 5 weight percent propane; and 1 to 98.9, preferably 14 to 69, and most preferably 33 to 5 weight percent HFC-125. 60 to 90, preferably 75 to 85, and most preferably 80.0 weight percent HFC-125; 5 to 20, preferably 10 to 15, and most preferably 15.0 weight percent HFC-161; and 3 to 15, preferably to 10, and most preferably 5.0 weight percent HFC-134a. 30 to 50, preferably 35 to 45, and most preferably 37.0 weight percent HCFC-22; 20 to 60 preferably 25 to 40, and most preferably 28.0 weight percent HFC-143a; and 10 to 45, preferabl 30 to 40, and most preferably 35.0 weight percen FC-218. There are other ternary and higher blends having these desirable characteristics that could be formulated by those skilled in the art from the halocarbons defined and exemplified herein. For example, other blends that may be formulated for the purposes of this invention are: TABLE IV Liquid Weight Percentage Most Blend Components Acceptable Preferred Preferred HFC-125/HFC-143a/ 35-65/30-60/ 45-55/35-45/ 50/40/5/5 HFC-134/HFC-134a 3-15/3-15 3-10/3-10 HFC-125/HFC-143a/ 35-65/30-60/ 35-50/30-40/ 40/35/5/20 HFC-134a/HCFC-22 3-15/30-55 3-10/15-25 HFC-125/HFC-143a/ 35-65/30-60 45-55/30-40/ 50/35/10/5 HFC-134a/HFC-124a 3-20/3-15 5-15/3-10 In addition, more than one halocarbon can be selected from each of the temperature ranges. The objective of this description is not to identify every possible blend composition, but to illustrate our discovery of the unexpected properties that the ternary (or higher) blends can take on, depending on the components, and the chosen compositions. The refrigerant of the instant invention can be prepared by a simple mixing process as is well known to those skilled in the art. Specific examples of the present invention will now be set forth. Unless otherwise stated, all percentages are by weight. It is to be understood that these examples are merely illustrative and are in no way to be interpreted as limiting the scope of this invention. F AMP E; i Impact of Vapor Leakage on Vapor Pressure at 24*C. TABLE V Vapor Pressures Refrigerant/ 0% Evaporated 80% Evaporated Composition psia (KPa) psia (KPa) %Chang R-502 171.1 (1180) 171.1 (1180) 0.0 HFC-125/HFC-143a/ 176.2 (1215) 165.2 (1139) 6.2 HFC-134a(55/40/5) HFC-125/HFC-143a/ 176.3 (1216) 164.3 (1133) 6.8 HFC-134(55/40/5) HFC-125/HFC-143a/ 179.0 (1234) 173.4 (1196) 3.1 HFC-124a(55/40/5) HFC-125/HFC-143a/ 178.2 (1229) 169.1 (1166) 5.1 HFC-124(55/40/5) HFC-125/HFC-143a/ 179.1 (1235) 171.5 (1182) 4.2 HFC-227ea(55/40/5) HFC-125/HFC-143a/ 179.5 (1238) 174.8 (1205) 2.6 FC-C216(55/40/5) HFC-125/HFC-143a/ 170.3 (1174) 160.1 (1104) 6.0 * HCFC-22(20/35/45) HCFC-22/HFC-143a/ 160.8 (1109) 156.8 (1081) 4.0 HFC-134a(45/50/5) HCFC-22/Propane/ 206.3 (1422) 187.4 (1292) 9.2 HFC-125(45/10/45) HFC-125/HFC-161/ 194.1 (1338) 181.7 (1253) 12.4 HFC-134a(80/15/5) HCFC-22/HFC-143a/ 174.7 (1205) 160.0 (1103) 8.4 FC-218(37/28/35) * 87% evaporated Example 1 demonstrates that all of the near-azeotropic blends of the present invention exhibit very low vapor pressure changes after 80 or -12- more percent by weight of the charge was leaked aw This vapor pressure versus leak performance behavi closely approximates that of a Refrigerant-502 alo The vapor pressure performance indicates that the near-azeotropic blends would maintain their vapor pressure characteristics, even if 80 weight percen the refrigerant were to be lost. HFC-227ca is very similar to HFC-227ea a can be substituted therefore in similar proportion 10 15 20 25 30 35 EXAMPLE 2 TABLE VI Refrigerant Performance Compεasior Exit Refrigerant Capacity COP Praaiura Teαp DT Coσoojltlon Btu/mln tkW)* Dili (KPa) R-502 8800..11((11440077))11..8899 282(1944) 239(115) .0 ( .0) HFC-125 8822..22((11*46622))11..6699 327(2255) 223(106) .0 ( .0) HFC-125/HFC-143a/ 8822..77((11445533))11..8822 307(2117) 227(108) .8 ( .4) HFC-134a (55/40/5) HFC-125/HFC-143a/ 82.6(1451)1.83 307(2117) 229(109) 1.1 ( .6) HFC-134 (55/40/5) HFC-125/HFC-143a/ 80.5(1414)1.82 304(2096) 229(109) 2.0(1.0) HFC-124 (55/40/5) HFC-125/HFC-143a/ 81.4(1430)1.81 307(2117) 226(108) 1.4 ( .7) HFC-227«» (55/40/5) HFC-125/HFC-143./ 85.6(1504)1.93 291(2006) 255(124) .7 ( .4) HCFC-22 (20/35/45) HCFC-22/HFC-143a/ 81.1(1425)1.96 277(1910) 256(123) .6 ( .3) HFC-134* (45/50/5) BCFC-22/Pcopana/ 80.1(1407)1.88 290(1999) 253(123) 1.6 (.9) HFC-125 (45/10/45) BFC-125/HFC-161/ 74.5(1309)1.81 294(2027) 239(115) 1.5 (.8) HFC-134a (80/15/5) BCFC-22/HFC-143*/ 79.4(1395)1.90 282(1944) 232(111) .1 (.1) FC-218 (35/40/25) Conditions test were run under: Condenser Temp 115*F (46*C) Evaporator Temp -30*F (-34*C) Suction superheated to Temp 95*F (35*C) Heat Exchanger used in refrigeration cycle Compressor Efficiency assumed 1.0 * based on a compressor displacement of 3.5 ft 3 /min (0.099 m 3 /min) ** represents condensing temperature differential across condenser Exa ple 2 data suggest that the near-azeotropic blends compare quite favorably with the commercial Refrigerant-502 refrigeration performance. Also, pentafluoroethane (HFC-125) , the refrigerant recognized by the refrigeration industr as a plausible substitute for Refrigerant-502 has a 10-15 percent decrease in energy efficiency. Energ efficiency is measured by coefficient of performanc (COP) . Therefore, the present blends of chlorodifluoromethane (HCFC-22) and/or pentafluoroethane (HFC-125) with one or more additional components exhibit a substantial improvement in energy efficiency. All the blends ha better energy efficiencies than pentafluoroethane (HFC-125) alone and some better than Refrigerant-502 HCFC-124a is very similar to HCFC-124 and can be substituted therefore in similar proportions, HFC-227ca is very similar to HFC-227ea and can be substituted therefore in similar proportions, and FC-C216 can be substituted as a third component givi similar refrigeration performance. EXAMPLE 3 - COMPARATIVE EXAMPLE A blend was prepared consisting of liquid concentrations of 57.9% pentafluoroethane (HFC-125) and 42.1% 1,1,1-trifluoroethane. (HFC-143a) . The vapo pressure of the blend was 185.5 psia (1279 KPa) at 2 deg Celcius. After 84.6% of the initial blend charg was lost via a vapor leak, the liquid composition ha changed to 53.2% HFC-125 and 46.8% HFC-143a. The vapor composition of HFC-143a was 39.1% initially an increased to 44.3%. The vapor pressure decreased to 172.5 psia (1189 KPa). The conclusion of this test was the HFC-143a composition would continue to increase during the remainder of the leak and this blend will become flammable; therefore, a third component is necessary when blending HFC-125 and HFC-143a to prevent the blend from becoming flammable. EXAMPLE 4 - COMPARATIVE EXAMPLE A blend was prepared consisting of liquid concentrations of 55.8% pentafluoroethane (HFC-125), 38.4% 1,1,1-trifluoroethane (HFC-143a) , and 5.8% 1,2,2,2-tetrafluoroethane (HFC-134a) . The ozone depletion potential of the blend is 0 and the global warming potential was calculated to be 0.68. Compare with Refrigerant-502 the blend has no ozone depletion potential and a 87% reduction in global warming potential. The vapor pressure was within 5% of the vapor pressure of Refrigerant-502 over the temperature range of -50 - 100 deg Celcius. At 24 deg Celcius, the blend had a vapor pressure of 176.2 psia (1215 KPa) compared with a vapor pressure of 171.1 psia (1180 KPa) for Refrigerant-502. To illustrate the surprisingly small changes in vapor pressure with compositional changes that occur during vapor leaks, vapor was allowed to leak from a suitable container holding the liquid blend and equilibrium vapor. After 96% of the initial blend charge had been lost via the vapor leak, the liquid compositions had changed to 45.9% HFC-125, 37.3% HFC-143a, and 16.8% HFC-134a. The vapor pressure after an 80% leak had decreased to 165.2 (1139 KPa) at 24 deg Celcius, being within 3.5% of the Refrigerant-502 vapor pressure. To illustrate the nonflammability of the blend, liquid and vapor samples were analyzed at the beginning and end of the leak test as well as vapor samples taken at blend charge weight losses of 5 to 95% in increments of 5%. The highest HFC-143a concentration was 39.2% in the vapor at 69.6% weight loss. At this point, the total vapor content was 53.8% HFC-125, 39.2% HFC-143a, and 7.0% HFC-134a. lower flammability limit at this point of HFC-125 a HFC-143a is above 39.2% at room temperature, therefore, with only 39.2% HFC-143a the blend is nonflammable at room temperature and atmospheric pressure. EXAMPLE 5 - COMPARATIVE EXAMPLE Another blend was prepared consisting of liquid compositions of 53.7% pentafluoroethane (HFC-125), 41.0% 1,1,1-trifluoroethane (HFC-143a) , a 5.3% 1,1,2,2-tetrafluoroethane (HFC-134) . The ozone depletion potential of the blend is 0 and the global warming potential was calculated to be 0.68. Compa with Refrigerant-502 the blend has no ozone depletio potential and a 87% reduction in global warming potential. The vapor pressure of the blend was 176. psia (1216 KPa) at 24 deg Celcius compared with 17 1 psia (1180 KPa) for Refrigerant-502. After 97.7% of the initial blend charge was lost via a vapor leak, the liquid compositions had changed to 43.3% HFC-125 39.0% HFC-143a, and 17.7% HFC-134. The vapor pressu after 80% leak had decreased to 164.3 psia (1133 KPa at 24 deg Celcius, being within 6.4% of the Refrigerant-502 vapor pressure. The highest HFC-143 concentration was 42.7% in the vapor at 35% weight loss. At this point, the total vapor content was 51.0% HFC-125, 42.7% HFC-143a, and 6.3% HFC-134. Again, experimentally, the maximum nonflammable concentration of HFC-143a in HFC-125 at any air concentration is above 42.7% at room temperature; therefore, with only 42.7% HFC-143a, the blend is nonflammable at room temperature and atmospheric pressure. EXAMPLE 6 - COMPARATIVE EXAMPLE Another blend was prepared consisting of liquid compositions of 20.7% pentafluoroethane (HFC-125), 35.7% 1,l,1-trifluoroethane (HFC-143a) , an 43.6% chlorodifluoromethane (HCFC-22). The ozone depletion potential was calculated to be 0.02 and the global warming potential 0.56. A 92% and 89% reduction in ozone depletion and global warming potentials, respectively. The vapor pressure of the blend was 170.3 psia (1174 KPa) at 24 deg Celcius compared with 171.1 psia (1180 KPa) for Refrigerant-502. After 87 % of the initial blend charge was lost via a vapor leak, the liquid composition had changed to 8.6% HFC-125, 30.3% HFC-143a, and 61.1% HCFC-22. The vapor pressure had decreased to 160.1 psia (1104 KPa) at 24 deg Celcius being within 6.5% of the Refrigerant-502 vapor pressure. The highest HFC-143a concentration was 36.9% in the vapor at 46.4% weight loss, again being nonflammable blend at room temperature and atmospheri pressure. EXAMPLE 7 - COMPARATIVE EXAMPLE A blend was prepared consisting of liquid concentrations of 37.2% chlorodifluoromethane (HCFC-22), 28.1% 1,1,1-trifluoroethane (HFC-143a) , an 34.7% octafluoropropane (FC-218). The ozone depletio of the blend is 0.02 and the global warming potential is dependent on the concentration of FC-218. Compare with Refrigerant-502 the blend has lower ozone depletion potential and may be formulated to have lower or equal global warming potential to Refrigerant-502. At 24 deg Celcius, the blend had a vapor pressure of 174.7 psia (1205 KPa) compared with the vapor pressure of 171.1 psia (1180 KPa) for Refrigerant-502. To illustrate the surprisingly small chang in vapor pressure with compositional changes that occur during vapor leaks, vapor was allowed to leak from a suitable container holding the liquid blend a equilibrium vapor. After 95.6% of the initial blen charge had been lost via the vapor leak, the liquid compositions had changed to 50.3% HCFC-22, 30.3% HFC-143a, and 19.4% FC-218. The vapor pressure afte an 80% leak had decreased to 168.4 psia (1161 KPa) a 24 deg Celcius, being within 2% of the Refrigerant-5 vapor pressure. Due to the increase in HFC-143a liquid composition the vapor was allowed to continue leaking. Initial liquid compositions were again measured at 50.7% HCFC-22, 30.9% HFC-143a, and 18.4% FC-218. After 94.5% of the blend charge at the abov liquid compositions had been lost after further evaporation via a vapor leak, the liquid composition had changed to 74.0% HCFC-22, 25.4% HFC-143a, and 0. FC-218. Again, the vapor pressure after an 80% leak had decreased to 160.0 psia (110 3 KPa) at 24 deg Celsius, being within 6.5% of the Refrigerant-502 vapor pressure. To illustrate the nonflammability of the blend, liquid and vapor samples were analyzed at the beginning and end of both leak tests as well as vapo samples taken at blend charge weight losses of 5 to 95% in increments of 5%. The highest HFC-143a concentration was 33.4% in the vapor at 78.8% weight loss during the continued leak test. At this point, the total vapor content was 56.4% HCFC-22, 33.4% HFC-143a, and 10.2% FC-218. Experimentally, the maximum nonflammable concentration of HFC-143a in HFC-125 at any air concentration is above 33.4% HFC-143a at room temperature, therefore, with only 33.4% HFC-143a, the blend is nonflammable at room temperature and atmospheric pressure. EXAMPLE 8 - COMPARATIVE EXAMPLE A commercial icemaker was used to evaluate the performance of the near-azeotrope blends with Refrigerant-502. High and low side pressure were measured as well as inlet and exit temperature around the condenser, evaporator, and compressor. The energy consumption was measured and the quality and quantity of ice produced. For similar operating conditions the blends of HCFC-22/HFC-143a/HFC-125, HFC-125/HFC-143a/HFC-134a, and HFC-125/Propane/HCFC-22 performed essentially the same as Refrigrant-502. EXAMPLE 9 - COMPARATIVE EXAMPLE A study shows that a mixture of HCFC-22, propane, and HFC-125 at the following composition is constant boiling. Allowing 50 weight percent of the mixture to leak out as vapor at room temperature the vapor pressure changes less than 10 percent. (IQ) is initial liquid composition, (FQ) is final liquid composition, (1-5) is vapor compositions, (VP) is vapor pressure, (DP) is change in vapor pressure from original mixture, and (leakage) represents the weight % leakage. L V I T E VIII TABLE XIV TABLE XVII TABLE XVIII TABLE XIX TABLE XX Additional fluorocarbons, ethers, and hydrocarbons can be added to HCFC-22 and HFC-125 comprising effective amounts of ethane, butane, isobutane, dimethyl ether (DME) , propylene, and difluoromethane (HFC-32) to make mixtures which are constant-boiling and could be useful as replacements for Refrigerant-502 and other medium-to-low-tempera- ture refrigerants. This Example is not intended to identify all compositions of these constant-boiling mixtures, but rather to show that these mixtures are constant boiling. A study shows that mixtures of HCFC-22 and HFC-125 with the following additional compounds in varing amounts in Table XXI form constant-boiling mixtures. Impact of Vapor Leakage on Vapor Pressure at 25*C TABLE XXI Vapor Pressures Refrigerant/ 0% Evaporated 50% Evaporated Composition psia psia %Chang HCFC-22/HFC-125/ Ethane (49/49/2) 206.7 187.7 9.2 HCFC-22/HFC-125/ Butane (49/49/2) 181.8 177.1 2.6 HCFC-22/HFC-125/ Isobutane (49/49/2) 183.4 179.5 2.1 HCFC-22/HFC-125/ DME (49/49/2) 178.2 170.0 4.6 HCFC-22/HFC-125/ Propylene (49/49/2) 186.1 182.1 2.1 HCFC-22/HFC-125/ HFC-32 (40/40/20) 216.6 210.0 3.0 Additional components from Table I, II, or III could be added to form quaternary and greater mixtures. Fo example, a mixture of HCFC-22/HFC-125/HFC-32/HFC-134a and/or HFC-134 could be formed.

Claims: WE CLAIM: 1. A near-azeotropic composition comprising pentafluoroethane and/or chlorodifluoromethane selected from the group consisting of 35 to 65 percent by weight pentafluoroethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, and 3 to 15 percent by weight 1,2,2,2-tetrafluoroethane; 35 to 65 percent by weigh pentafluoroethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, and 3 to 15 percent by weight 1,1,2,2-tetrafluoroethane; 35 to 65 percent by weigh pentafluoroethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, and 3 to 15 percent by weight 1-chloro-l,1,2,2-tetrafluoroethane; 35 to 65 percent by weight pentafluoroethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, and 3 to 15 percent by weight 1-chloro-l,2,2,2-tetrafluoroethane; 35 to 65 percent by weight pentafluoroethane, 30 to 60 percen by weight 1,1,1-trifluoroethane, and 3 to 15 percent by weight 1,1,1,2,3,3,3-heptafluoropropane; 35 to 65 percent by weight pentafluoroethane, 30 to 60 percen by weight 1,1,1-trifluoroethane, and 3 to 15 percen by weight 1,1,1,2,2,3,3-heptafluoropropane; 35 to 65 percent by weight pentafluoroethane, 30 to 60 percen by weight 1,1,1-trifluoroethane, and 3 to 15 percent by weight hexafluorocyclopropane; 5 to 30 percent by weight pentafluoroethane, 30 to 60 percent by weigh 1,1,1-trifluoroethane, and 30 to 55 percent by weigh chlorodifluoromethane; 30 to 55 percent by weight chlorodifluoromethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, and 3 to 15 percent 1,2,2,2-tetrafluoroethane; 1 to 98.9 percent by weig chlorodifluoromethane, o.l to 15 percent by weight propane, and 1.0 to 98.9 percent by weight pentafluoroethane; 60 to 90 percent by weight pentafluoroethane, 5 to 20 percent by weight fluoroethane, and 3 to 15 percent by weight 1,2,2,2-tetrafluoroethane; 30 to 50 percent by weight chlorodifluoromethane, 20 to 60 percent by weight 1,1,1-trifluoroethane, and 10 to 45 percent by weight octafluoropropane; 35 to 65 percent by weight pentafluoroethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, 3 to 15 percent by weight 1,1,2,2-tetrafluoroethane, and 3 to 15 percent by weight 1,2,2,2-tetrafluoroethane; 35 to 65 percent by weight pentafluoroethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, 3 to 15 percent by weight 1,2,2,2-tetrafluoroethane, and 30 to 55 percent by weight chlorodifluoromethane; 35 to 65 percent by weight pentafluoroethane, 30 to 60 percent by weight 1,1,1-trifluoroethane, 3 to 20 percent by weight 1,2,2,2-tetrafluoroethane, and 3 to 15 percent by weight 1-chloro-l,1,2,2-tetrafluoroethane; 35 to 65 percent by weight chlorodifluoromethane, 34 to 64 percent by weight pentafluoroethane and 1 to 15 percent by weight ethane; 35 to 65 percent by weight chlorodifluoromethane, 34 to 64 percent by weight pentafluoroethane and 1 to 15 percent by weight butane; 35 to 65 percent by weight chlorodifluoromethane, 34 to 64 percent by weight pentafluoroethane and 1 to 15 percent by weight isobutane; 35 to 65 percent by weight chlorodifluoromethane, 34 to 64 percent by weight pentafluoroethane and 1 to 15 percent by weight dimethyl ether; 35 to 65 percent by weight chlorodifluoromethane, 34 to 64 percent by weight pentafluoroethane and 1 to 15 percent by weight propylene; 15 to 85 percent by weight chlorodifluoromethane, 10 to 80 percent by weight pentafluoroethane and 5 to 45 percent by weight difluoromethane. 2. A near-azeotropic composition of Clai 1 consisting essentially of 50 to 60 percent by weig pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight 1,2,2,2-tetrafluoroethane. 3. A near-azeotropic composition of Clai 2 consisting essentially of about 55.0 percent by weight pentafluoroethane, about 40.0 percent by weig 1,1,1-trifluoroethane, and about 5.0 percent by weig 1,2,2,2-tetrafluoroethane. 4. A near-azeotropic composition c-f Clai 1 consistinc. essentially of 50 to 60 percent by weig pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight 1,1,2,2-tetrafluoroethane. 5. A near-azeotropic composition of Clai 4 consisting essentially of about 55.0 percent by weight pentafluoroethane, about 40.0 percent by weig 1,1,1-trifluoroethane, and about 5.0 percent by weig 1,1,2,2-tetrafluoroethane. 6. A near-azeotropic composition of Claim 1 consisting essentially of 50 to 60 percent by weigh pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight 1-chloro-l,1,2,2-tetrafluoroethane. 7. A near-azeotropic composition of Claim 6 consisting assentially of about 55.0 percent by weight pentafluoroethane, about 40.0 percent by weigh 1,1,1-trifluoroethane, and about 5.0 percent by weigh 1-chloro-l,1,2,2-tetrafluoroethane. 8. A near-azeotropic composition of Claim consisting essentially of 50 to 60 percent by weight pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight 1-chloro-l,2,2,2-tetrafluoroethane. 9. A near-azeotropic composition of Claim consisting essentially of about 55.0 percent by weigh pentafluoroethane, about 40.0 percent by weight 1,1,1-trifluoroethane, and about 5.0 percent by weigh 1-chloro-l,2,2,2-tetrafluoroethane. 10. A near-azeotropic composition of Claim 1 consisting essentially of 50 to 60 percent by weigh pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight 1,1,1,2,3,3,3-heptafluoropropane. 11. A near-azeotropic composition of Claim 10 consisting essentially of about 55.0 percent by weight pentafluoroethane, about 40.0 percent by weigh 1,1,1-trifluoroethane, and about 5.0 percent by weigh 1,1,1,2,3,3,3-heptafluoropropane. 12. A near-azeotropic composition of Claim 1 consisting essentially of 50 to 60 percent by weigh pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight 1,1,1,2,2,3,3-heptafluoropropane. 13. A near-azeotropic composition of Claim 12 consisting essentially of about 55.0 percent by weight pentafluoroethane, about 40.0 percent by weigh 1,1,1-trifluoroethane, and about 5.0 percent by weigh 1,1,1,2,2,3,3-heptafluoropropane. 14. A near-azeotropic composition of Clai 1 consisting essentially of 50 to 60 percent by weig pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight hexafluorocyclopropane. 15. A near-azeotropic composition of Clai 14 consisting essentially of about 55.0 percent by weight pentafluoroethane, about 40.0 percent by weig 1,1,1-trifluoroethane, and about 5.0 percent by weig hexafluorocyclopropane. 16. A near-azeotropic composition of Clai 1 consisting essentially of 15 to 25 percent by weig pentafluoroethane, 30 to 40 percent by weight 1,1,1-trifluoroethane, and 40 to 50 percent by weigh chlorodifluoromethane. 17. A near-azeotropic composition of Clai 16 consisting essentially of about 20.0 percent by weight pentafluoroethane, about 35.0 percent by weig 1,1,1-trifluoroethane, and about 45.0 percent by weight chlorodifluoromethane. 18. A near-azeotropic composition of Clai 1 consisting essentially of 40 to 50 percent by weig chlorodifluoromethane, 45 to 55 percent by weight 1,1,1-trifluoroethane, and 3 to 10 percent by weight 1,2,2,2-tetrafluoroethane. 19. A near-azeotropic composition of Clai 18 consisting essentially of about 45.0 percent by weight chlorodifluoromethane, about 50.0 percent by weight 1,1,1-trifluoroethane, and about 5.0 percent weight 1,2,2,2-tetrafluoroethane. 20. A near-azeotropic composition of Claim 1 consisting essentially of 30 to 85 percent by weigh chlorodifluoromethane, 1 to 10 percent by weight propane, and 14 to 69 percent by weight pentafluoroethane. 21. A near-azeotropic composition of Claim 20 consisting essentially of about 45 to 65 percent b weight chlorodifluoromethane, about 2 to 5 percent by weight propane, and about 33 to 53 percent by weight pentafluoroethane. 22. A near-azeotropic composition of Claim 1 consisting essentially of 75 to 85 percent by weigh pentafluoroethane, 10 to 15 percent by weight fluoroethane, and 3 to 10 percent by weight 1,2,2,2-tetrafluoroethane. 23. A near-azeotropic composition of Claim 22 consisting essentially of about 80.0 percent by weight pentafluoroethane, about 15.0 percent by weigh fluoroethane, and about 5.0 percent by weight 1,2,2,2-tetrafluoroethane. 24. A near-azeotropic composition of Claim 1 consisting essentially of 35 to 45 percent by weigh chlorodifluoromethane, 25 to 40 percent by weight 1,1,1-trifluoroethane, and 30 to 40 percent by weight octafluoropropane. 25. A near-azeotropic composition of Claim 24 consisting essentially of about 37.0 percent by weight chlorodifluoromethane, about 28.0 percent by weight 1,1,1-trifluoroethane, and about 35.0 percent by weight octafluoropropane. 26. A near-azeotropic composition of Cl 1 consistis; :/ essentially of 45 to 55 percent by wei pentafluoroethane, 35 to 45 percent by weight 1,1,1-trifluoroethane, 3 to 10 percent by weight 5 1,1,2,2-tetrafluoroethane, and 3 to 10 percent by weight 1,2, 2,2-tetrafluoroethane. 27. A near-azeotropic composition of Cla 26 consisting essentially of about 50.0 percent by 10 weight pentafluoroethane, about 40.0 percent by wei 1,1,1-trifluoroethane, about 5.0 percent by weight 1,1,2,2-tetrafluoroethane, and about 5.0 percent by weight 1,2,2,2-tetrafluoroethane. 15 28. A near-azeotropic composition of Cla 1 consisting essentially of 35 to 50 percent by wei pentafluoroethane, 30 to 40 percent by weight 1,1,1-trifluoroethane, 3 to 10 percent by weight 1,2,2,2-tetrafluoroethane, and 15 to 25 percent by 20 weight chlorodifluoromethane. 29. A near-azeotropic composition of Cla 28 consisting essentially of about 40.0 percent by weight pentafluoroethane, about 35.0 percent by wei 25 1,1,1-trifluoroethane, about 5.0 percent by weight 1,2,2,2-tetrafluoroethane, and about 20.0 percent b weight chlorodifluoromethane. 30. A near-azeotropic composition of Cla 30 1 consisting essentially of 45 to 55 percent by wei pentafluoroethane, 30 to 40 percent by weight 1,1,1-trifluoroethane, 5 to 15 percent by weight 1,2,2,2-tetrafluoroethane, and 3 to 10 percent by weight 1-chloro-l,1,2,2-tetrafluoroethane. 35 31. A near-azeotropic composition of Claim 30 consisting essentially of about 50.0 percent by weight pentafluoroethane, about 35.0 percent by weigh 1,1,1-trifluoroethane, about 10.0 percent by weight 1,2,2,2-tetrafluoroethane, and about 5.0 percent by weight 1-chloro-l,1,2,2-tetrafluoroethane. 32. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 1 in the vicinity of a body to b cooled. 33. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 2 in the vicinity of a body to b cooled. 34. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 4 in the vicinity of a body to b cooled. 35. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 16 in the vicinity of a body to be cooled. 36. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 18 in the vicinity of a body to be cooled. 37. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 20 in the vicinity of a body t be cooled. 38. A process for producing refrigeratio which comprises evaporating a near-azeotropic 5 composition of Claim 22 in the vicinity of a body t be cooled. 39. A process for producing refrigeratio which comprises evaporating a near-azeotropic 1 0 composition of Claim 24 in the vicinity- of a body t be cooled. 40. A near azeotropic composition of Cla 1 consisting essentially of 45 to 55 percent by wei 15 chlorodifluoromethane, 44 to 54 percent by weight pentafluoroethane and 1 to 5 percent by weight etha 41. A near azeotropic composition of Cla 40 consisting essentially of 49 percent by weight 20 chlorodifluoromethane, 49 percent by weight pentafluoroethane and 2 percent by weight ethane. 42. A near azeotropic composition of Cla 1 consisting essentially of 45 to 55 percent by wei 25 chlorodifluoromethane, 44 to 54 percent by weight pentafluoroethane and 1 to 5 percent by weight buta 43. A near azeotropic composition of Cla 42 consisting essentially of 49 percent by weight 30 chlorodifluoromethane, 49 percent by weight pentafluoroethane and 2 percent by weight butane. 44. A near azeotropic composition of Cla 1 consisting essentially of 45 to 55 percent by wei 35 chlorodifluoromethane, 44 to 54 percent by weight pentafluoroethane and 1 to 5 percent by weight isobutane. 45. A near azeotropic composition of Claim 44 consisting essentially of 49 percent by weight chlorodifluoromethane, 49 percent by weight pentafluoroethane and 2 percent by weight isobutane. 46. A near azeotropic composition of Claim 1 consisting essentially of 45 to 55 percent by weight chlorodifluoromethane, 44 to 54 percent by weight pentafluoroethane and 1 to 5 percent by weight dimethyl ether. 47. A near azeotropic composition of Claim 46 consisting essentially of 49 percent by weight chlorodifluoromethane, 49 percent by weight pentafluoroethane and 2 percent by weight dimethyl ether. 48. A near azeotropic composition of Claim 1 consisting essentially of 45 to 55 percent by weight chlorodifluoromethane, 44 to 54 percent by weight pentafluoroethane and 1 to 5 percent by weight propylene. 49. A near azeotropic composition of Claim 48 consisting essentially of 49 percent by weight chlorodifluoromethane, 49 percent by weight pentafluoroethane and 2 percent by weight propylene. 50. A near azeotropic composition of Claim 1 consisting essentially of 30 to 50 percent by weight chlorodifluoromethane, 30 to 50 percent by weight pentafluoroethane and 10 to 30 percent by weight difluoromethane. 51. A near azeotropic composition of Clai 50 consisting essentially of 40 percent by weight chlorodifluoromethane, 40 percent by weight pentafluoroethane and 20 percent by weight difluoromethane. 52. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 6 in the vicinity of a body to b cooled. 53. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 8 in the vicinity of a body to b cooled. 54. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 10 in the vicinity of a body to be cooled. 55. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 12 in the vicinity of a body to be cooled. 56. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 14 in the vicinity of a body to be cooled. 57. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 26 in the vicinity of a body to be cooled. 58. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 28 in the vicinity of a body to be cooled. 59. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 30 in the vicinity of a body to be cooled. 60. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 40 in the vicinity of a body to be cooled. 61. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 42 in the vicinity of a body to be cooled. 62. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 44 in the vicinity of a body to be cooled. 63. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 46 in the vicinity of a body to be cooled. 64. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 48 in the vicinity of a body to be cooled. 65. A process for producing refrigeration which comprises evaporating a near-azeotropic composition of Claim 50 in the vicinity of a body to be cooled.

Inventors: BIVENS DONALD BERNARD, SHIFLETT MARK BRANDON, YOKOZEKI AKIMICHI, BIVENS, DONALD, BERNARD, SHIFLETT, MARK, BRANDON, YOKOZEKI, AKIMICHI
Applicants: DU PONT, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1991
Main classification: C09K5
IPC codes: C07C19, C07C23, C09K5, F25B1