Abstract:
This invention relates to compositions of a hexafluoropropane and a hydrofluorocarbon, with the hydrofluorocarbon being hexafluoropropane, pentafluoropropane, tetrafluoropropane, trifluoropropane, difluoropropane, fluoropropane, or (CF 3 ) 2  CHCH 3 . The compositions, which may be azeotropic or azeotrope-like, may be used as refrigerants, cleaning agents, expansion agents for polyolefins and polyurethanes, aerosol propellants, refrigerants, heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents or displacement drying agents.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of pending U.S. patent application Ser. No. 08/039,563, filed Mar. 29, 1993 now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to compositions of mixture of hydrofluorocarbons. These compositions are useful as cleaning agents, expansion agents for polyolefins and polyurethanes, aerosol propellants, refrigerants, heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, and displacement drying agents. 
     BACKGROUND OF THE INVENTION 
     Fluorinated hydrocarbons have many uses, one of which is as a refrigerant. Such refrigerants include dichlorodifluoromethane (CFC-12) and chlorodifluoromethane (HCFC-22). 
     In recent years it has been pointed out that certain kinds of fluorinated hydrocarbon refrigerants released into the atmosphere may adversely affect the stratospheric ozone layer. Although this proposition has not yet been completely established, there is a movement toward the control of the use and the production of certain chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) under an international agreement. 
     Accordingly, there is a demand for the development of refrigerants that have a lower ozone depletion potential than existing refrigerants while still achieving an acceptable performance in refrigeration applications. Hydrofluorocarbons (HFCs) have been suggested as replacements for CFCs and HCFCs since HFCs have no chlorine and therefore have zero ozone depletion potential. 
     In refrigeration applications, a refrigerant is often lost during operation through leaks in shaft seals, hose connections, soldered joints and broken lines. In addition, the refrigerant may be released to the atmosphere during maintenance procedures on refrigeration equipment. If the refrigerant is not a pure component or an azeotropic or azeotrope-like composition, the refrigerant composition may change when leaked or discharged to the atmosphere from the refrigeration equipment, which may cause the refrigerant to become flammable or to have poor refrigeration performance. 
     Accordingly, it is desirable to use as a refrigerant a single fluorinated hydrocarbon or an azeotropic or azeotrope-like composition that includes one or more fluorinated hydrocarbons. 
     Fluorinated hydrocarbons may also be used as a cleaning agent or solvent to clean, for example, electronic circuit boards. It is desirable that the cleaning agents be azeotropic or azeotrope-like because in vapor degreasing operations the cleaning agent is generally redistilled and reused for final rinse cleaning. 
     Azeotropic or azeotrope-like compositions that include a fluorinated hydrocarbon are also useful as blowing agents in the manufacture of closed-cell polyurethane, phenolic and thermoplastic foams, as propellants in aerosols, as heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids such as for heat pumps, inert media for polymerization reactions, fluids for removing particulates from metal surfaces, as carrier fluids that may be used, for example, to place a fine film of lubricant on metal parts, as buffing abrasive agents to remove buffing abrasive compounds from polished surfaces such as metal, as displacement drying agents for removing water, such as from jewelry or metal parts, as resist developers in conventional circuit manufacturing techniques including chlorine-type developing agents, or as strippers for photoresists when used with, for example, a chlorohydrocarbon such as 1,1,1-trichloroethane or trichloroethylene. 
     SUMMARY OF THE INVENTION 
     The present invention relates to the discovery of refrigerant compositions of hexafluoropropane and a hydrofluorocarbon, with the hydrofluorocarbon being hexafluoropropane, pentafluoropropane, tetrafluoropropane, trifluoropropane, difluoropropane, fluoropropane, or HFC-356mmz. These compositions are also useful as cleaning agents, expansion agents for polyolefins and polyurethanes, aerosol propellants, heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, and displacement drying agents. Further, the invention relates to the discovery of binary azeotropic or azeotrope-like compositions comprising effective amounts of hexafluoropropane and hexafluoropropane, pentafluoropropane, tetrafluoropropane, trifluoropropane, difluoropropane, fluoropropane, or HFC-356mmz to form an azeotropic or azeotrope-like composition. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-236fa at 25° C.; 
     FIG. 2 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-245eb at 25° C.; 
     FIG. 3 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-245fa at 25° C.; 
     FIG. 4 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-254eb at 25° C.; 
     FIG. 5 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-263ca at 25° C.; 
     FIG. 6 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-263fb at 25° C.; 
     FIG. 7 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-272ca at 25° C.; 
     FIG. 8 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-272fb at 25° C.; 
     FIG. 9 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-281ea at 25° C.; 
     FIG. 10 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ca and HFC-356mmz at 25° C.; 
     FIG. 11 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-236ea at 25° C.; 
     FIG. 12 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-236fa at 25° C.; 
     FIG. 13 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-245fa at 25° C.; 
     FIG. 14 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-254cb at 25° C.; 
     FIG. 15 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-254eb at 25° C.; 
     FIG. 16 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-263fb at 25° C.; 
     FIG. 17 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-272ca at 25° C.; 
     FIG. 18 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-281ea at 25° C.; 
     FIG. 19 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236cb and HFC-281fa at 25° C.; 
     FIG. 20 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ea and HFC-236fa at 25° C.; 
     FIG. 21 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ea and HFC-245cb at 25° C.; 
     FIG. 22 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ea and HFC-263fb at 25° C.; 
     FIG. 23 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ea and HFC-272ca at 25° C.; 
     FIG. 24 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ea and HFC-272fb at 25° C.; 
     FIG. 25 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ea and HFC-281ea at 25° C.; 
     FIG. 26 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236ea and HFC-281fa at 25° C.; 
     FIG. 27 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-245ca at 25° C.; 
     FIG. 28 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-245eb at 25° C.; 
     FIG. 29 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-254ca at 25° C.; 
     FIG. 30 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-254cb at 25° C.; 
     FIG. 31 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-254eb at 25° C.; 
     FIG. 32 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-272ca at 25° C.; 
     FIG. 33 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-272ea at 25° C.; 
     FIG. 34 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-281ea at 25° C.; and 
     FIG. 35 is a graph of the vapor/liquid equilibrium curve for mixtures of HFC-236fa and HFC-281fa at 25° C. 
    
    
     DETAILED DESCRIPTION 
     The present invention relates to the following compositions: 
     (a) 1,1,2,2,3,3-hexafluoropropane (HFC-236ca) and 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,2,3-pentafluoropropane (HFC-45eb), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,2,2-trifluoropropane (HFC-263ca), 1,1,1-trifluoropropane (HFC-263fb), 2,2-difluoropropane (HFC-272ca), 1,1-difluoropropane (HFC-272fb), 2-fluoropropane (HFC-281ea) or (CF 3 ) 2  CHCH 3  (HFC-356mmz); 
     (b) 1,1,1,2,2,3-hexafluoropropane (HFC-236cb) and 1,1,2,3,3,3-hexafluoropropane (HFC-236ea), HFC-236fa, HFC-245fa, 1,1,2,2-tetrafluoropropane (HFC-254cb), HFC-254eb, HFC-263fb, HFC-272ca, HFC-272fb, HFC-281ea or 1-fluoropropane (HFC-281fa); 
     (c) HFC-236ea and HFC-236fa, 1,1,1,2,2-pentafluoropropane (HFC-245cb), HFC-263fb, HFC-272ca, HFC-272fb, HFC-281ea or HFC-281fa; or 
     (d) HFC-236fa and 1,1,2,2,3-pentafluoropropane (HFC-245ca), HFC-245eb, 1,2,2,3-tetrafluoropropane (HFC-254ca), HFC-254cb, HFC-254eb, HFC-72ca, HFC-272ea, HFC-281ea or HFC-281fa. 
     1-99 wt. % of each of the components of the compositions can be used as refrigerants. Further, the present invention also relates to the discovery of azeotropic or azeotrope-like compositions of effective amounts of each of the above mixtures to form an azeotropic or azeotrope-like composition. 
     By &#34;azeotropic&#34; composition is meant a constant boiling liquid admixture of two or more substances that behaves as a single substance. One way to characterize an azeotropic composition is that the vapor produced by partial evaporation or distillation of the liquid has the same composition as the liquid from which it was evaporated or distilled, that is, the admixture distills/refluxes without compositional change. Constant boiling compositions are characterized as azeotropic because they exhibit either a maximum or minimum boiling point, as compared with that of the non-azeotropic mixtures of the same components. 
     By &#34;azeotrope-like&#34; composition is meant a constant boiling, or substantially constant boiling, liquid admixture of two or more substances that behaves as a single substance. One way to characterize an azeotrope-like composition is that the vapor produced by partial evaporation or distillation of the liquid has substantially the same composition as the liquid from which it was evaporated or distilled, that is, the admixture distills/refluxes without substantial composition change. 
     It is recognized in the art that a composition is azeotrope-like if, after 50 weight percent of the composition is removed such as by evaporation or boiling off, the difference in vapor pressure between the original composition and the composition remaining after 50 weight percent of the original composition has been removed is less than 10 percent, when measured in absolute units. By absolute units, it is meant measurements of pressure and, for example, psia, atmospheres, bars, torr, dynes per square centimeter, millimeters of mercury, inches of water and other equivalent terms well known in the art. If an azeotrope is present, there is no difference in vapor pressure between the original composition and the composition remaining after 50 weight percent of the original composition has been removed. 
     Therefore, included in this invention are compositions of effective amounts of 
     (a) 1,1,2,2,3,3-hexafluoropropane (HFC-236ca) and 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,2,2-trifluoropropane (HFC-263ca), 1,1,1-trifluoropropane (HFC-263fb), 2,2-difluoropropane (HFC-272ca), 1,1-difluoropropane (HFC-272fb), 2-fluoropropane (HFC-281ea) or (CF3)2CHCH 3  (HFC-356mmz); 
     (b) 1,1,1,2,2,3-hexafluoropropane (HFC-236cb) and 1,1,2,3,3,3-hexafluoropropane (HFC-236ea), HFC-236fa, HFC-245fa, 1,1,2,2-tetrafluoropropane (HFC-254cb), HFC-254eb, HFC-263fb, HFC-272ca, HFC-272fb, HFC-281ea or HFC-281fa; 
     (c) HFC-236ea and HFC-236fa, HFC-245cb, HFC-263fb, HFC-272ca, HFC-272fb, HFC-281ea or HFC-281fa; or 
     (d) HFC-236fa and HFC-245ca, HFC-245eb, HFC-254ca, HFC-254cb, HFC-254eb, HFC-272ca, HFC-272ea, HFC-281ea or HFC-281fa; 
     such that after 50 weight percent of an original composition is evaporated or boiled off to produce a remaining composition, the difference in the vapor pressure between the original composition and the remaining composition is 10 percent or less. 
     For compositions that are azeotropic, there is usually some range of compositions around the azeotrope point that, for a maximum boiling azeotrope, have boiling points at a particular pressure higher than the pure components of the composition at that pressure and have vapor pressures at a particular temperature lower than the pure components of the composition at that temperature, and that, for a minimum boiling azeotrope, have boiling points at a particular pressure lower than the pure components of the composition at that pressure and have vapor pressures at a particular temperature higher than the pure components of the composition at that temperature. Boiling temperatures and vapor pressures above or below that of the pure components are caused by unexpected intermolecular forces between and among the molecules of the compositions, which can be a combination of repulsive and attractive forces such as van der Waals forces and hydrogen bonding. 
     The range of compositions that have a maximum or minimum boiling point at a particular pressure, or a maximum or minimum vapor pressure at a particular temperature, may or may not be coextensive with the range of compositions that have a change in vapor pressure of less than about 10% when 50 weight percent of the composition is evaporated. In those cases where the range of compositions that have maximum or minimum boiling temperatures at a particular pressure, or maximum or minimum vapor pressures at a particular temperature, are broader than the range of compositions that have a change in vapor pressure of less than about 10% when 50 weight percent of the composition is evaporated, the unexpected intermolecular forces are nonetheless believed important in that the refrigerant compositions having those forces that are not substantially constant boiling may exhibit unexpected increases in the capacity or efficiency versus the components of the refrigerant composition. 
     The components of the compositions of this invention have the following vapor pressures at 25° C. 
     
         ______________________________________Components        Psia   kPa______________________________________HFC-236ca         24.9   172HFC-236cb         33.6   232HFC-236ea         29.8   206HFC-236fa         39.4   271HFC-245ca         14.2   98HFC-245cb         67.4   465HFC-245eb         16.9   117HFC-245fa         21.6   149HFC-254ca         13.7   95HFC-254cb         34.2   236HFC-254eb         34.8   240HFC-263ca         18.2   126HFC-263fb         54.0   372HFC-272ca         34.5   238HFC-272ea         20.8   143HFC-272fb         26.5   182HFC-281ea         47.1   325HFC-281fa         37.7   260HFC-356mmz        16.6   114______________________________________ 
    
     Substantially constant boiling, azeotropic or azeotrope-like compositions of this invention comprise the following (all compositions are measured at 25° C.): 
     
         ______________________________________           WEIGHT           RANGES      PREFERREDCOMPONENTS      (wt. %/wt/%)                       (wt. %/wt. %)______________________________________HFC-236ca/HFC-236fa           1-99/1-99    1-80/20-99HFC-236ca/HFC-245eb           1-99/1-99    1-85/15-99HFC-236ca/HFC-245fa           1-99/1-99   20-99/1-80HFC-236ca/HFC-254eb           1-99/1-99   40-99/1-60HFC-236ca/HFC-263ca           1-99/1-99   20-99/1-80HFC-236ca/HFC-263fb            1-62/38-99  1-62/38-99HFC-236ca/HFC-272ca            1-81/19-99 20-81/19-80HFC-236ca/HFC-272fb           1-99/1-99   30-99/1-70HFC-236ca/HFC-281ea            1-78/22-99  1-78/22-99HFC-236ca/HFC-356mmz           1-99/1-99   50-99/1-50HFC-236cb/HFC-236ea           1-99/1-99   1-99/1-99HFC-236cb/HFC-236fa           1-99/1-99   1-99/1-99HFC-236cb/HFC-245fa           1-99/1-99   1-60/40-99HFC-236cb/HFC-254cb           1-99/1-99   20-99/1-80HFC-236cb/HFC-254eb           1-99/1-99   20-99/1-80HFC-236cb/HFC-263fb           1-99/1-99   1-99/1-99HFC-236cb/HFC-272ca           1-99/1-99   40-99/1-60HFC-236cb/HFC-272fb           1-99/1-99   20-99/1-80HFC-236cb/HFC-281ea           1-99/1-99   20-99/1-80HFC-236cb/HFC-281fa           1-99/1-99   20-99/1-80HFC-236ea/HFC-236fa           1-99/1-99   1-99/1-99HFC-236ea/HFC-245cb            1-45/55-99  1-45/55-99HFC-236ea/HFC-263fb            1-65/35-99  1-65/35-99HFC-236ea/HFC-272ca           1-99/1-99   20-99/1-80HFC-236ea/HFC-272fb           1-99/1-99   40-99/1-60HFC-236ea/HFC-281ea            1-87/13-99 15-87/13-85HFC-236ea/HFC-281fa           1-99/1-99   20-99/1-80HFC-236fa/HFC-245ca           72-99/1-28  72-99/1-28HFC-236fa/HFC-245eb           60-99/1-40  60-99/1-40HFC-236fa/HFC-254ca           68-99/1-32  68-99/1-32HFC-236fa/HFC-254cb           1-99.8/0.2-99                       49-99.8/0.2-60HFC-236fa/HFC-254eb           1-99/1-99   40-99/1-60HFC-236fa/HFC-272ca           1-99/1-99   40-99/1-60HFC-236fa/HFC-272ea           64-99/1-36  64-99/1-36HFC-236fa/HFC-281ea           1-99/1-99   40-99/1-60HFC-236fa/HFC-281fa           1-99/1-99   40-99/1-60______________________________________ 
    
     For purposes of this invention, &#34;effective amount&#34; is defined as the amount of each component of the inventive compositions which, when combined, results in the formation of an azeotropic or azeotrope-like composition. This definition includes the amounts of each component, which amounts may vary depending on the pressure applied to the composition so long as the azeotropic or azeotrope-like compositions continue to exist at the different pressures, but with possible different boiling points. 
     Therefore, effective amount includes the amounts, such as may be expressed in weight percentages, of each component of the compositions of the instant invention which form azeotropic or azeotrope-like compositions at temperatures or pressures other than as described herein. 
     For the purposes of this discussion, azeotropic or constant-boiling is intended to mean also essentially azeotropic or essentially-constant boiling. In other words, included within the meaning of these terms are not only the true azeotropes described above, but also other compositions containing the same components in different proportions, which are true azeotropes at other temperatures and pressures, as well as those equivalent compositions which are part of the same azeotropic system and are azeotrope-like in their properties. As is well recognized in this art, there is a range of compositions which contain the same components as the azeotrope, which will not only exhibit essentially equivalent properties for refrigeration and other applications, but which will also exhibit essentially equivalent properties to the true azeotropic composition in terms of constant boiling characteristics or tendency not to segregate or fractionate on boiling. 
     It is possible to characterize, in effect, a constant boiling admixture which may appear under many guises, depending upon the conditions chosen, by any of several criteria: 
     * The composition can be defined as an azeotrope of A, B, C (and D . . . ) since the very term &#34;azeotrope&#34; is at once both definitive and limitative, and requires that effective amounts of A, B, C (and D . . . ) for this unique composition of matter which is a constant boiling composition. 
     * It is well known by those skilled in the art, that, at different pressures, the composition of a given azeotrope will vary at least to some degree, and changes in pressure will also change, at least to some degree, the boiling point temperature. Thus, an azeotrope of A, B, C (and D . . . ) represents a unique type of relationship but with a variable composition which depends on temperature and/or pressure. Therefore, compositional ranges, rather than fixed compositions, are often used to define azeotropes. 
     * The composition can be defined as a particular weight percent relationship or mole percent relationship of A, B, C (and D . . . ), while recognizing that such specific values point out only one particular relationship and that in actuality, a series of such relationships, represented by A, B, C (and D . . . ) actually exist for a given azeotrope, varied by the influence of pressure. 
     * An azeotrope of A, B, C (and D . . . ) can be characterized by defining the compositions as an azeotrope characterized by a boiling point at a given pressure, thus giving identifying characteristics without unduly limiting the scope of the invention by a specific numerical composition, which is limited by and is only as accurate as the analytical equipment available. 
     The azeotrope or azeotrope-like compositions of the present invention can be prepared by any convenient method including mixing or combining the desired amounts. A preferred method is to weigh the desired component amounts and thereafter combine them in an appropriate container. 
     Specific examples illustrating the invention are given below. Unless otherwise stated therein, all percentages are by weight. It is to be understood that these examples are merely illustrative and in no way are to be interpreted as limiting the scope of the invention. 
     EXAMPLE 1 
     Phase Study 
     A phase study shows the following compositions are azeotropic, all at 25° C. 
     
         ______________________________________                   Vapor Press.Composition No.         psia (kPa)______________________________________HFC-236ca/HFC-236fa              7.6/92.4 39.5   272HFC-236ca/HFC-245eb              9.1/90.9 16.9   117HFC-236ca/HFC-245fa             98.3/1.7  24.9   172HFC-236ca/HFC-254eb             77.4/22.6 21.7   150HFC-236ca/HFC-263ca             35.4/64.6 17.8   123HFC-236ca/HFC-263fb             13.7/86.3 54.6   376HFC-236ca/HFC-272ca             46.8/53.2 40.2   277HFC-236ca/HFC-272fb             56.1/43.9 29.0   200HFC-236ca/HFC-281ea             16.3/83.7 47.4   327HFC-236ca/HFC-356mmz             78.1/21.9 25.8   178HFC-236cb/HFC-236ea             36.7/63.3 27.6   190HFC-236cb/HFC-236fa             28.2/71.8 41.7   288HFC-236cb/HFC-245fa             25.6/74.4 20.5   141HFC-236cb/HFC-254cb             52.1/47.9 28.8   199HFC-236cb/HFC-254eb             39.0/61.0 35.2   243HFC-236cb/HFC-263fb             19.0/81.0 55.0   379HFC-236cb/HFC-272ca             58.2/41.8 41.3   285HFC-236cb/HFC-272fb             45.0/55.0 26.1   180HFC-236cb/HFC-281ea             39.1/60.9 48.9   337HFC-236cb/HFC-281fa             56.1/43.9 40.4   279HFC-236ea/HFC-236fa             17.6/82.4 41.4   285HFC-236ea/HFC-245cb              3.7/96.3 67.6   466HFC-236ea/HFC-263fb             20.0/80.0 56.2   387HFC-236ea/HFC-272ca             50.0/50.0 41.7   288HFC-236ea/HFC-272fb             75.0/25.0 31.0   214HFC-236ea/HFC-281ea             33.9/66.1 48.7   336HFC-236ea/HFC-281fa             44.8/55.2 39.9   275HFC-236fa/HFC-245ca             98.0/2.0  39.5   272HFC-236fa/HFC-245eb             90.4/9.6  40.6   280HFC-236fa/HFC-254ca             92.4/7.6  40.8   281HFC-236fa/HFC-254cb             99.8/0.2  39.4   272HFC-236fa/HFC-254eb             74.4/25.6 41.5   286HFC-236fa/HFC-272ca             79.3/20.7 40.6   280HFC-236fa/HFC-272ea             88.9/11.1 43.2   298HFC-236fa/HFC-281ea             62.5/37.5 54.0   372HFC-236fa/HFC-281fa             75.3/24.7 48.4   334______________________________________ 
    
     EXAMPLE 2 
     Impact of Vapor Leakage on Vapor Pressure at 25° C. 
     A vessel is charged with an initial composition at 25° C., and the initial vapor pressure of the composition is measured. The composition is allowed to leak from the vessel, while the temperature is held constant at 25° C., until 50 weight percent of the initial composition is removed, at which time the vapor pressure of the composition remaining in the vessel is measured. The results are summarized below. 
     
         ______________________________________       INITIAL  50% LEAK   DELTAWT % A/WT % B PSIA    KPA    PSIA  KPA  % P______________________________________HFC-236ca/HFC-236fa7.6/92.4      39.5    272    39.5  272  0.01/99          39.4    272    39.4  272  0.040/60         37.8    261    37.2  256  1.660/40         35.4    244    33.6  232  5.190/20         31.5    217    28.8  199  8.685/15         30.2    208    27.6  190  8.699/1          25.4    175    25.1  173  1.2HFC-236ca/HFC-245eb9.1/90.9      16.9    117    16.9  117  0.01/99          16.9    117    16.9  117  0.040/60         17.4    120    17.3  119  0.660/40         20.     138    19.1  132  4.585/15         22.5    155    21.4  148  4.999/1          24.8    171    24.8  171  0.0HFC-236ca/HFC-245fa98.3/1.7      24.9    172    24.9  172  0.099/1          24.9    172    24.9  172  0.060/40         24.4    168    24.3  168  0.440/60         23.7    163    23.6  163  0.420/80         22.8    157    22.7  157  0.41/99          21.7    150    21.7  150  0.0HFC-236ca/HFC-254eb77.4/22.6     21.7    150    21.7  150  0.090/10         23.     159    22.5  155  2.299/1          24.8    171    24.8  171  0.050/50         25.2    174    23.5  162  6.745/55         26.1    180    24.2  167  7.340/60         27.1    187    25.1  173  7.430/70         29.2    201    27.1  187  7.220/80         31.1    214    29.5  203  5.11/99          34.6    239    34.5  238  0.3HFC-236ca/HFC-263ca35.4/64.6     17.8    123    17.8  123  0.020/80         17.9    123    17.9  123  0.01/99          18.2    125    18.2  125  0.060/40         18.4    127    18.2  125  1.180/20         20.6    142    19.7  136  4.490/10         22.7    157    21.7  150  4.499/1          24.8    171    24.7  170  0.4HFC-236ca/HFC-263fb13.7/86.3     54.6    376    54.6  376  0.01/99          54.1    373    54.1  373  0.040/60         53.1    366    52.   359  2.160/40         49.8    343    45.4  313  8.865/35         48.5    334    42.7  294  12.63/37         49.     338    43.8  302  10.662/38         49.3    340    44.4  306  9.9HFC-236ca/HFC-272ca46.8/53.2     40.2    277    40.2  277  0.020/80         38.8    268    37.5  259  3.41/99          34.9    241    34.6  239  0.910/90         37.2    256    35.8  247  3.870/30         39.     269    37.6  259  3.685/15         35.7    246    31.2  215  12.682/18         36.7    253    32.8  226  10.681/19         36.9    254    33.3  230  9.8HFC-236ca/HFC-272fb56.1/43.9     29.     200    29.   200  0.030/70         28.4    196    28.2  194  0.710/90         27.2    188    27.   186  0.71/99          26.5    183    26.5  183  0.080/20         28.2    194    27.9  192  1.199/1          25.2    174    25.1  173  0.4HFC-236ca/HFC-281ea16.3/83.7     47.4    327    47.4  327  0.01/99          47.2    325    47.2  325  0.040/60         46.8    323    46.5  321  0.660/40         45.     310    43.7  301  2.980/20         40.6    280    36.1  249  11.178/22         41.3    285    37.2  256  9.9HFC-236ca/HFC-356mmz78.1/21.9     25.8    178    25.8  178  0.090/10         25.6    177    25.5  176  0.499/1          25.     172    25.   172  0.050/50         24.9    172    24.3  168  2.430/70         23.     159    21.4  148  7.20/80         21.6    149    19.5  134  9.718/82         21.2    146    19.2  132  9.410/90         19.5    134    17.8  123  8.71/99          16.9    117    16.7  115  1.2HFC-236cb/HFC-236ea36.7/63.3     27.6    190    27.6  190  0.020/80         28.3    195    28.1  194  0.71/99          29.9    206    29.9  206  0.060/40         28.7    198    28.4  196  4.580/20         30.9    213    30.4  210  1.699/1          33.5    231    33.4  230  0.3HFC-236cb/HFC-236fa28.2/71.8     41.7    288    41.7  288  0.015/85         41.3    285    41.2  284  0.21/99          39.6    273    39.5  272  0.360/40         40.     276    39.5  272  1.380/20         37.5    259    36.6  252  2.499/1          33.8    233    33.8  233  0.0HFC-236cb/HFC-245fa25.6/74.4     20.5    141    20.5  141  0.010/90         21.3    147    21.1  145  0.91/99          21.7    150    21.7  150  0.060/40         24.4    168    22.7  157  7.65/35         25.4    175    23.5  162  7.570/30         26.5    183    24.4  168  7.980/20         28.8    199    26.9  185  6.699/1          33.4    230    33.2  229  0.6HFC-236cb/HFC-254cb52.1/47.9     28.8    199    28.8  199  0.080/20         30.7    212    30.3  209  1.399/1          33.4    230    33.4  230  0.020/80         31.7    219    30.9  213  2.51/99          34.2    236    34.2  236  0.0HFC-236cb/HFC-254eb39/61         35.2    243    35.2  243  0.020/80         35.1    242    35.1  242  0.01/99          34.8    240    34.8  240  0.070/30         34.8    240    34.8  240  0.090/10         34.2    236    34.1  235  0.399/1          33.7    232    33.7  232  0.0HFC-236cb/HFC-263fb19/81         55.     379    55.   379  0.010/90         54.8    378    54.8  378  0.01/99          54.1    373    54.1  373  0.050/50         53.     365    51.7  356  2.580/20         45.4    313    41.3  285  9.82/18         44.6    308    40.4  279  9.484/16         43.7    301    39.5  272  9.685/15         43.2    298    39.1  270  9.599/1          34.4    237    33.9  234  1.5HFC-236cb/HFC-272ca58.2/41.8     41.3    285    41.3  285  0.080/20         40.     276    39.3  271  1.899/1          34.2    236    33.9  234  0.920/80         38.8    268    37.4  258  3.61/99          34.8    240    34.6  239  0.6HFC-236cb/HFC-272fb45/55         26.1    180    26.1  180  0.020/80         26.7    184    26.7  184  0.01/99          26.7    184    26.5  183  0.775/25         28.1    194    27.5  190  2.199/1          33.3    230    33.2  229  0.3HFC-236cb/HFC-281ea39.1/60.9     48.9    337    48.9  337  0.020/80         48.5    334    48.4  334  0.21/99          47.2    325    47.2  325  0.070/30         47.1    325    46.1  318  2.185/15         43.5    300    41.1  283  5.592/8          40.1    276    37.6  259  6.299/1          34.7    239    34.1  235  1.7HFC-236cb/HFC-281fa56.1/43.9     40.4    279    40.4  279  0.080/20         39.2    270    38.8  268  1.99/1          34.1    235    34.   234  0.320/80         39.1    270    38.9  268  0.51/99          37.8    261    37.8  261  0.0HFC-236ea/HFC-236fa17.6/82.4     41.4    285    41.4  285  0.01/99          39.7    274    39.6  273  0.340/60         40.2    277    39.6  273  1.560/40         37.6    259    36.3  250  3.580/20         34.1    235    32.8  226  3.899/1          30.1    208    30.0  207  0.3HFC-236ea/HFC-245cb3.7/96.3      67.6    466    67.6  466  0.01/99          67.5    465    67.5  465  0.020/80         65.9    454    64.8  447  1.740/60         61.1    421    56.3  388  7.945/55         59.5    410    53.6  370  9.946/54         59.2    408    53.0  365  10.5HFC-236ea/HFC-263fb20.0/80.0     56.2    387    56.2  387  0.01/99          54.3    374    54.2  374  0.250/50         53.7    370    51.5  355  4.165/35         50.2    346    45.4  313  9.666/34         49.9    344    44.9  310  10.0HFC-236ea/HFC-272ca50.0/50.0     41.7    288    41.7  288  0.025/75         40.6    280    39.2  270  3.41/99          35.0    241    34.6  239  1.175/25         40.0    276    38.7  267  3.299/1          30.6    211    30.1  208  1.6HFC-236ea/HFC-272fb75.0/25.0     31.0    214    31.0  214  0.099/1          30.0    207    29.9  206  0.340/60         29.9    206    29.6  204  1.020/80         28.5    197    28.0  193  1.81/99          26.6    183    26.5  183  0.4HFC-236ea/HFC-281ea33.9/66.1     48.7    336    48.7  336  0.015/85         48.2    332    48.1  332  0.21/99          47.2    325    47.2  325  0.060/40         47.5    328    46.8  323  1.580/20         43.7    301    40.5  279  7.387/13         40.8    281    36.8  254  9.888/12         40.3    278    36.2  250  10.2HFC-236ea/HFC-281fa44.8/55.2     39.9    275    39.9  275  0.020/80         39.2    270    39.0  269  0.51/99          37.8    261    37.8  261  0.060/40         39.6    273    39.4  272  0.580/20         37.4    258    36.4  251  2.799/1          30.5    210    30.2  208  1.0HFC-236fa/HFC-245ca98/2          39.5    272    39.5  272  0.099/1          39.4    272    39.4  272  0.060/40         32.9    227    27.4  189  16.770/30         35.4    244    31.5  217  11.72/28         35.8    247    32.4  223  9.5HFC-236fa/HFC-245eb90.4/9.6      40.6    280    40.6  280  0.099/1          39.7    274    39.6  273  0.360/40         37.6    259    34.1  235  9.359/41         37.5    259    33.7  232  10.1HFC-236fa/HFC-254ca92.4/7.6      40.8    281    40.8  281  0.099/1          39.9    275    39.6  273  0.860/40         36.9    254    30.7  212  16.870/30         38.7    267    35.6  245  8.67/33         38.3    264    34.3  236  10.468/32         38.4    265    34.8  240  9.4HFC-236fa/HFC-254cb99.8/0.2      39.4    272    39.4  272  0.070/30         38.8    268    38.7  267  0.340/60         37.3    257    37.1  256  0.520/80         35.9    248    35.7  246  0.61/99          34.3    236    34.2  236  0.3HFC-236fa/HFC-254eb74.4/25.6     41.5    286    41.5  286  0.090/10         40.9    282    40.7  281  0.599/1          39.6    273    39.5  272  0.340/60         39.7    274    39.3  271  1.20/80         37.6    259    37.   255  1.61/99          34.9    241    34.9  241  0.0HFC-236fa/HFC-272ca79.3/20.7     40.6    280    40.6  280  0.090/10         40.3    278    40.3  278  0.099/1          39.5    272    39.5  272  0.040/60         38.7    267    38.2  263  1.320/80         36.9    254    36.3  250  1.61/99          34.6    239    34.6  239  0.0HFC-236fa/HFC-272ea88.9/11.1     43.2    298    43.2  298  0.099/1          40.6    280    39.8  274  2.60/40         39.6    273    34.6  239  12.665/35         40.6    280    36.9  254  9.164/36         40.4    279    36.4  251  9.9HFC-236fa/HFC-281ea62.5/37.5     54.     372    54.   372  0.080/20         52.8    364    51.7  356  2.190/10         49.7    343    46.5  321  6.495/5          46.2    319    42.6  294  7.899/1          41.2    284    39.9  275  3.240/60         52.8    364    52.2  360  1.120/80         50.4    347    49.4  341  2.10/90         48.9    337    48.2  332  1.41/99          47.3    326    47.2  325  0.2HFC-236fa/HFC-281fa75.3/24.7     48.4    334    48.4  334  0.090/10         46.9    323    45.6  314  2.899/1          40.9    282    39.9  275  2.440/60         45.2    312    43.3  299  4.220/80         41.8    288    39.9  275  4.510/90         39.8    274    38.6  266  3.1/99          37.9    261    37.8  261  0.3______________________________________ 
    
     The results of this Example show that these compositions are azeotropic or azeotrope-like because when 50 wt. % of an original composition is removed, the vapor pressure of the remaining composition is within about 10% of the vapor pressure of the original composition, at a temperature of 25° C. 
     EXAMPLE 3 
     Impact of Vapor Leakage at -25° C. 
     A leak test is performed on compositions of HFC-236fa and HFC-272ea, at the temperature of -25° C. The results are summarized below. 
     
         ______________________________________WT % A/WT % B INITIAL    50% LEAK   DELTAHFC-236fa/HFC-272ea         PSIA    KPA    PSIA  KPA  % P______________________________________87.9/12.1     5.68    39.2   5.68  39.2 0.099/1          5.27    36.3   5.05  34.8 4.264/36         5.34    36.8   4.84  33.4 9.463/37         5.32    36.7   4.78  33.0 10.2______________________________________ 
    
     These results show that compositions of HFC-236fa and HFC-272ea are azeotropic or azeotrope-like at different temperatures, but that the weight percents of the components vary as the temperature is changed. 
     EXAMPLE 4 
     Refrigerant Performance 
     The following table shows the performance of various refrigerants. The data are based on the following conditions. 
     Evaporator temperature 48.0° F. (8.9° C.) 
     Condenser temperature 115.0° F. (46.1° C.) 
     Subcooled 12.0° F. (6.7° C.) 
     Return gas 65.0° F. (18.3° C.) 
     Compressor efficiency is 75%. 
     The refrigeration capacity is based on a compressor with a fixed displacement of 3.5 cubic feet per minute and 75% volumetric efficiency. Capacity is intended to mean the change in enthalpy of the refrigerant in the evaporator per pound of refrigerant circulated, i.e. the heat removed by the refrigerant in the evaporator per time. Coefficient of performance (COP) is intended to mean the ratio of the capacity to compressor work. It is a measure of refrigerant energy efficiency. 
     
         ______________________________________                                   Capacity    Evap.    Cond.    Comp. Dis.   BTU/Refrig.  Press.   Press.   Temp. °F.                                   minComp.    Psia(kPa)             Psia(kPa)                      (°C.)                              COP  (kw)______________________________________CFC-11   8(55)    30(207)  167(75) 5.10  50(0.9)HCFC-22  95(655)  258(1779)                      183(84) 4.60 397(7.0)HFC-236ca/HFC-236fa1.0/99.0 21(145)  69(476)  129(54) 4.71 103(1.8)7.6/92.4 21(145)  69(476)  129(54) 4.71 102(1.8)95.0/5.0 14(97)   50(345)  134(57) 4.85  77(1.4)HFC-236ca/HFC-245eb1.0/99.0 9(62)    34(234)  139(59) 4.95  53(0.9)9.1/90.9 9(62)    35(241)  138(59) 4.95  54(1.0)95.0/5.0 14(97)   48(331)  134(57) 4.85  73(1.3)HFC-236ca/HFC-245fa5.0/95.0 12(83)   43(296)  137(58) 4.9   66(1.2)98.3/1.7 14(97)   48(331)  134(57) 4.85  74(1.3)99.0/1.0 14(97)   49(338)  134(57) 4.85  74(1.3)HFC-236ca/HFC-254eb5.0/95.0 20(138)  64(441)  137(58) 4.85 100(1.8)77.4/22.6    15(103)  53(365)  135(57) 4.86  81(1.4)95.0/5.0 14(97)   50(345)  134(57) 4.84  76(1.3)HFC-236ca/HFC-263ca5.0/95.0 10(69)   36(248)  143(62) 4.99  57(1.0)35.4/64.6    11(76)   39(269)  141(61) 4.96  62(1.1)95.0/5.0 14(97)   48(331)  135(57) 4.85  73(1.3)HFC-236ca/HFC-263fb5.0/95.0 31(214)  95(655)  137(58) 4.76 145(2.6)13.7/86.3    30(207)  91(627)  137(58) 4.77 139(2.4)95.0/5.0 15(103)  51(352)  134(57) 4.87  79(1.4)HFC-236ca/HFC-272ca5.0/95.0 20(138)  63(434)  142(61) 4.92 100(1.8)46.8/53.2    18(124)  59(407)  139(59) 4.96  94(1.7)95.0/5.0 14(97)   50(345)  135(57) 4.85  77(1.4)HFC-236ca/HFC-272fb5.0/95.0 15(103)  51(352)  148(64) 4.99  81(1.4)56.1/43.9    15(103)  52(359)  141(61) 4.92  82(1.4)95.0/5.0 14(97)   50(345)  135(57) 4.86  76(1.3)HFC-236ca/HFC-281ea5.0/95.0 28(193)  84(579)  147(64) 4.92 135(2.4)16.3/83.7    27(186)  82(565)  146(63) 4.91 132(2.3)95.0/5.0 15(103)  53(365)  135(57) 4.88  81(1.4)HFC-236ca/HFC-356mmz5.0/95.0 9(62)    34(234)  123(51) 4.78  50(0.9)78.1/21.9    13(90)   45(310)  131(55) 4.83  69(1.2)95.0/5.0 14(97)   48(331)  133(56) 4.84  73(1.3)HFC-236cb/HFC-236ea5.0/95.0 16(110)  56(386)  133(56) 4.81  85(1.5)36.7/63.3    17(117)  58(400)  132(56) 4.79  88(1.5)95.0/5.0 19(131)  63(434)  130(54) 4.74  95(1.7)HFC-236cb/HFC-236fa5.0/95.0 21(145)  69(476)  129(54) 4.71 103(1.8)28.2/71.8    21(145)  67(462)  129(54) 4.71 100(1.8)95.0/5.0 19(131)  64(441)  129(54) 4.74  95(1.7)HFC-236cb/HFC-245fa5.0/95.0 12(83)   43(296)  137(58) 4.9   67(1.2)25.6/74.4    14(97)   47(324)  135(57) 4.89  73(1.3)95.0/5.0 19(131)  62(427)  130(54) 4.74  94(1.7)HFC-236cb/HFC-254cb5.0/95.0 20(138)  64(441)  136(58) 4.85  99(1.7)52.1/47.9    20(138)  64(441)  133(56) 4.8   98(1.7)95.0/5.0 19(131)  64(441)  130(54) 4.75  96(1.7)HFC-236cb/HFC-254eb5.0/95.0 20(138)  65(448)  136(58) 4.85 101(1.8)39.0/61.0    20(138)  65(448)  134(57) 4.81 100(1.8)95.0/5.0 20(138)  64(441)  130(54) 4.75  96(1.7)HFC-236cb/HFC-263fb5.0/95.0 32(221)  96(662)  137(58) 4.76 146(2.6)19.0/81.0    30(207)  93(641)  136(58) 4.76 141(2.5)95.0/5.0 20(138)  66(455)  130(54) 4.75  99(1.7)HFC-236cb/HFC-272ca5.0/95.0 20(138)  63(434)  141(61) 4.93 101(1.8)58.2/41.8    21(145)  66(455)  135(57) 4.84 102(1.8)95.0/5.0 20(138)  64(441)  130(54) 4.75  97(1.7)HFC-236cb/HFC-272fb5.0/95.0 15(103)  51(352)  147(64) 5     83(1.5)45.0/55.0    18(124)  59(407)  141(61) 4.91  92(1.6)95.0/5.0 20(138)  64(441)  130(54) 4.76  96(1.7)HFC-236cb/HFC-281ea5.0/95.0 28(193)  85(586)  147(64) 4.92 136(2.4)39.1/60.9    28(193)  84(579)  142(61) 4.87 133(2.3)95.0/5.0 21(145)  67(462)  131(55) 4.76 102(1.8)HFC-236cb/HFC-281fa5.0/95.0 22(152)  70(483)  148(64) 4.94 112(2.0)56.1/43.9    23(159)  73(503)  140(60) 4.86 114(2.0)95.0/5.0 20(138)  66(455)  131(55) 4.76 100(1.8)HFC-236ea/HFC-236fa5.0/95.0 21(145)  69(476)  129(54) 4.71 102(1.8)17.6/82.4    21(145)  67(462)  130(54) 4.74 100(1.8)95.0/5.0 16(110)  56(386)  133(56) 4.8   85(1.5)HFC-236ea/HFC-245cb1.0/99.0 38(262)  111(765) 124(51) 4.55 159(2.8)3.7/96.3 37(255)  109(752) 124(51) 4.56 157(2.8)95.0/5.0 17(117)  58(400)  133(56) 4.82  88(1.5)HFC-236ea/HFC-263fb5.0/95.0 32(221)  96(662)  137(58) 4.76 146(2.6)20.0/80.0    29(200)  91(627)  137(58) 4.78 138(2.4)95.0/5.0 17(117)  58(400)  134(57) 4.82  89(1.6)HFC-236ea/HFC-272ca5.0/95.0 20(138)  63(434)  141(61) 4.93 101(1.8)50.0150.0    19(131)  61(421)  138(59) 4.89  97(1.7)95.0/5.0 17(117)  57(393)  134(57) 4.82  86(1.5)HFC-236ea/HFC-272fb5.0/95.0 15(103)  51(352)  148(64) 4.98  82(1.4)75.0/25.0    17(117)  56(386)  138(59) 4.87  88(1.5)95.0/5.0 16(110)  56(386)  134(57) 4.82  86(1.5)HFC-236ea/HFC-281ea5.0/95.0 28(193)  85(586)  147(64) 4.91 135(2.4)33.9/66.1    26(179)  81(558)  145(63) 4.89 128(2.3)95.0/5.0 18(124)  59(407)  135(57) 4.84  91(1.6)HFC-236ea/HFC-281fa5.0/95.0 22(152)  70(483)  148(64) 4.95 112(2.0)44.8/55.2    21(145)  69(476)  144(62) 4.91 109(1.9)95.0/5.0 17(117)  58(400)  135(57) 4.83  89(1.6)HFC-236fa/HFC-245ca5.0/95.0 8(55)    30(207)  139(59) 5.0   47(0.8)98.0/2.0 21(145)  68(469)  129(54) 4.71 101(1.8)99.0/1.0 21(145)  69(476)  129(54) 4.71 102(1.8)HFC-236fa/HFC-245eb5.0/95.0 10(69)   35(241)  138(59) 4.96  55(1.0)90.4/9.6 20(138)  65(448)  130(54) 4.75  97(1.7)99.0/1.0 21(145)  69(476)  129(54) 4.71 103(1.8)HFC-236fa/HFC-254ca5.0/95.0 8(55)    29(200)  142(61) 5.05  46(0.8)92.4/7.6 19(131)  64(441)  130(54) 4.75  96(1.7)99.0/1.0 21(145)  69(476)  129(54) 4.71 102(1.8)HFC-236fa/HFC-254cb5.0/95.0 20(138)  64(441)  136(58) 4.85 100(1.8)99.8/0.2 21(145)  69(476)  129(54) 4.71 103(1.8)HFC-236fa/HFC-254eb5.0/95.0 20(138)  65(448)  136(58) 4.84 101(1.8)74.4/25.6    21(145)  69(476)  131(55) 4.75 104(1.8)95.0/5.0 21(145)  69(476)  129(54) 4.72 103(1.8)HFC-236fa/HFC-272ca5.0/95.0 20(138)  64(441)  141(61) 4.92 102(1.8)79.3/20.7    22(152)  70(483)  132(56) 4.78 106(1.9)95.0/5.0 22(152)  70(483)  130(54) 4.73 104(1.8)HFC-236fa/HFC-272ea5.0/95.0 12(83)   41(283)  149(65) 5.05  67(1.2)88.9/11.1    21(145)  67(462)  132(56) 4.76 101(1.8)95.0/5.0 21(145)  68(469)  130(54) 4.73 102(1.8)HFC-236fa/HFC-281ea5.0/95.0 28(193)  85(586)  147(64) 4.92 136(2.4)62.5/37.5    27(186)  84(579)  138(59) 4.82 130(2.3)95.0/5.0 23(159)  73(503)  131(55) 4.73 109(1.9)HFC-236fa/HFC-281fa5.0/95.0 22(152)  70(483)  148(64) 4.95 113(2.0)75.3/24.7    24(165)  76(524)  136(58) 4.79 116(2.0)95.0/5.0 22(152)  72(496)  130(54) 4.73 107(1.9)______________________________________ 
    
     EXAMPLE 5 
     This Example is directed to measurements of the liquid/vapor equilibrium curves for the mixtures in FIGS. 1-35. 
     Turning to FIG. 1, the upper curve represents the composition of the liquid, and the lower curve represents the composition of the vapor. 
     The data for the compositions of the liquid in Figure I are obtained as follows. A stainless steel cylinder is evacuated, and a weighed amount of HFC-236ca is added to the cylinder. The cylinder is cooled to reduce the vapor pressure of HFC-236ca, and then a weighed amount of HFC-236fa is added to the cylinder. The cylinder is agitated to mix the HFC-236ca and HFC-236fa, and then the cylinder is placed in a constant temperature bath until the temperature comes to equilibrium at 25° C., at which time the vapor pressure of the HFC-236ca and HFC236fa in the cylinder is measured. Additional samples of liquid are measured the same way, and the results are plotted in FIG. 1. 
     The curve which shows the composition of the vapor is calculated using an ideal gas equation of state. 
     Vapor/liquid equilibrium data are obtained in the same way for the mixtures shown in FIGS. 2-35. 
     The data in FIGS. 1, 3, 6-10, 12 and 15-35 show that at 25° C., there are ranges of compositions that have vapor pressures higher than the vapor pressures of the pure components of the composition at that same temperature. As stated earlier, the higher than expected pressures of these compositions may result in an unexpected increase in the refrigeration capacity or efficiency of those compositions when compared to the pure components of the compositions. 
     The data in FIGS. 2, 4-5, 11 and 13-14 show that at 25° C., there are ranges of compositions that have vapor pressures below the vapor pressures of the pure components of the composition at that same temperature. These minimum boiling compositions are useful in refrigeration, and may show an improved efficiency when compared to the pure components of the composition. 
     The novel compositions of this invention, including the azeotropic or azeotrope-like compositions, may be used to produce refrigeration by condensing the compositions and thereafter evaporating the condensate in the vicinity of a body to be cooled. The novel compositions may also be used to produce heat by condensing the refrigerant in the vicinity of the body to be heated and thereafter evaporating the refrigerant. 
     In addition to refrigeration applications, the novel constant boiling or substantially constant boiling compositions of the invention are also useful as aerosol propellants, heat transfer media, gaseous dielectrics, fire extinguishing agents, expansion agents for polyolefins and polyurethanes and power cycle working fluids. 
     ADDITIONAL COMPOUNDS 
     Other components, such as aliphatic hydrocarbons having a boiling point of -60° to +60° C., hydrofluorocarbonalkanes having a boiling point of -60° to 60° C., hydrofluoropropanes having a boiling point of between -60° to +60° C., hydrocarbon esters having a boiling point between -60° to +60° C., hydrochlorofluorocarbons having a boiling point between -60° to +60° C., hydrofluorocarbons having a boiling point of -60° to +60° C., hydrochlorocarbons having a boiling point between -60° to +60° C., chlorocarbons and perfluorinated compounds, can be added to the azeotropic or azeotrope-like compositions described above without substantially changing the properties thereof, including the constant boiling behavior, of the compositions. 
     Additives such as lubricants, corrosion inhibitors, surfactants, stabilizers, dyes and other appropriate materials may be added to the novel compositions of the invention for a variety of purposes provides they do not have an adverse influence on the composition for its intended application. Preferred lubricants include esters having a molecular weight greater than 250.