FIELD OF THE INVENTION This invention relates to compositions that include at least two hydrofluorocarbons. These compositions are useful as refrigerants, cleaning agents, expansion agents for polyolefins and polyurethanes, aerosol propeUants, heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids, polymerization media, paniculate 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-11) 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-Uke compositions that include a fluorinated hydrocarbon are also useful as blowing agents in the manufacture of closed-cell polyurethane, phenohc and thermoplastic foams, as propeUants 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 poUshed 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 compositions of trifluoromethane (HFC-23) and pentafluoropropane; fluoromethane (HFC-41) and pentafluoropropane; tetrafluoroethane and heptafluoropropane or pentafluoropropane; 1,1-difluoroethane (HFC-152a) and heptafluoropropane, or pentafluoropropane; heptafluoropropane and pentafluoropropane, tetrafluoropropane, trifluoropropane, difluoropropane, or fiuoropropane; or 1,1,1,2,2,3,3-heptafluoropropane (HFC-227ca) and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). These compositions are useful as refrigerants, cleaning agents, expansion agents for polyolefins and polyurethanes, aerosol propeUants, heat transfer media, gaseous dielectrics, fire extinguishing agents, power cycle working fluids, polymerization media, paniculate removal fluids, carrier fluids, buffing abrasive agents, and displacement drying agents. Further, the invention relates to the discovery of binary azeotropic or azeotrope-Uke compositions comprising

effective amounts of these components to form an azeotropic or azeotrope-like composition.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-23 and HFC-245cb at 25°C;

Figure 2 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-41 and HFC-245cb at 25°C;

Figure 3 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-134a and HFC-227ca at 11.2°C; Figure 4 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-134a and HFC-227ea at 11.2°C;

Figure 5 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-134a and HFC-245cb at 25°C;

Figure 6 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-152a and HFC-227ca at 11.2°C;

Figure 7 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-152a and HFC-227ea at -10.0°C;

Figure 8 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC- 152a and HFC-245cb at 25°C; Figure 9 is a graph of the vapor/Uquid eqmlibrium curve for mixtures of HFC-227ca and HFC-227ea at 25°C;

Figure 10 is a graph of the vapor/liquid equiUbrium curve for mixtures of HFC-227ca and HFC-245cb at 25°C;

Figure 11 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-227ca and HFC-263fb at 25°C;

Figure 12 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-227ca and HFC-272ca at 25°C;

Figure 13 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-227ca and HFC-281ea at 25°C; Figure 14 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-227ea and HFC-245cb at 25°C;

Figure 15 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-227ea and HFC-245fa at 25°C;

Figure 16 is a graph of the vapor/Uquid equiUbrium curve for mixtures of HFC-227ea and HFC-254cb at 25°C;

Figure 17 is a graph of the vapor/Uquid equilibrium curve for mixtures of HFC-227ea and HFC-263fb at 25°C; and

Figure 18 is a graph of the vapor/liquid equiUbrium curve for mixtures of HFC-227ea and HFC-281ea at 25°C.

DETAILED DESCRIPTION

The present invention relates to the following compositions: trifluoromethane (HFC-23) and pentafluoropropane; fluoromethane (HFC-41) and pentafluoropropane; tetrafluoroethane and heptafluoropropane or pentafluoropropane; 1,1-difluoroethane (HFC- 152a) and heptafluoropropane, or pentafluoropropane; heptafluoropropane and pentafluoropropane, tetrafluoropropane, trifluoropropane, difluoropropane, or fiuoropropane; or 1,1,1,2,2,3,3-heptafluoropropane (HFC-227ca) and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). Specific compositions include trifluoromethane (HFC-23) and 1,1,1,2,2-pentafluoropropane (HFC-245cb); fluoromethane (HFC-41) and 1,1,1,2,2- pentafluoropropane (HFC-245cb); 1,1,1,2-tetrafluoroethane (HFC- 134a), and 1, 1, 1,2,2,3,3-heptafluoropropane (HFC-227ca), 1, 1, 1,2,3,3,3-heptafluoropropane (HFC-227ea)or 1,1,1,2,2-pentafluoropropane (HFC-245cb); 1,1-difluoroethane (HFC- 152a) and 1,1,1,2,2,3,3-heptafluoropropane (HFC-227ca), 1,1,1,2,3,3,3- heptafluoropropane (HFC-227ea) or 1,1,1,2,2-pentafluoropropane (HFC-245cb); 1,1,1,2,2,3,3-heptafluoropropane (HFC-227ca) and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,1-trifluoropropane (HFC-263fb), 2,2-difluoroproρane (HFC-272ca), or 2-fluoropropane (HFC-281ea); or 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) and 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,2,2- tetrafluoropropane (HFC-254cb), 1,1,1-trifluoropropane (HFC-263fb) or 2- fluoropropane (HFC-281ea).

1-99 wt.% of each of the components in the above compositions can be used as refrigerants. As used herein, the term "heptafluoropropane" includes 1,1,1,2,2,3,3-heptafluoropropane (HFC-227ca) and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea); the term "pentafluoropropane" includes 1,1,2,2,3-pentafluoropropane (HFC-245ca), 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,2,3,3- pentafluoropropane (HFC-245ea), 1,1,1,2,3-pentafluoropropane (HFC-245eb) and 1,1,1,3,3-pentafluoropropane (HFC-245fa); the term "tetrafluoropropane" includes 1,2,2,3-tetrafluoropropane (HFC-254ca), 1,1,2,2-tetrafluoropropane (HFC-254cb), 1,1,2,3-tetrafluoropropane (HFC-254ea), 1,1,1,2-tetrafluoropropane (HFC-254eb),

1,1,3,3-tetrafluoroρropane (HFC-254fa) and 1,3,3,3-tetrafluoropropane (HFC- 254fb); the term "trifluoropropane" includes 1,2,2-trifluoropropane (HFC-263ca), 1,2,3-trifluoroρropane (HFC-263ea), 1,1,2-trifluoroρroρane (HFC-263eb), 1,1,3- trifluoropropane (HFC-263fa) and 1,1,1-trifluoropropane (HFC-263fb); the term "difluoropropane" includes 2,2-difluoropropane (HFC-272ca), 1,2-difluoropropane (HFC-272ea), 1,3-difluoropropane (HFC-272fa) and 1,1-difluoropropane (HFC- 272fb); and the term "fiuoropropane" includes 2-fluoropropane (HFC-281ea) and 1- fluoropropane (HFC-281fa).

The present invention also relates to the discovery of azeotropic or azeotrope-Uke compositions of effective amounts of HFC-23 and HFC-245cb; HFC-41 and HFC-245cb; HFC-134a and HFC-227ca, HFC-227ea or HFC-245cb; HFC-152a and HFC-227ca, HFC-227ea or HFC-245cb; HFC-227ca and HFC- 227ea, HFC-245cb, HFC-263fb, HFC-272ca, or HFC-281ea; or HFC-227ea and HFC-245cb, HFC-245fa, HFC-254cb, HFC-263fb or HFC-281ea to form an azeotropic or azeotrope-like composition. By "azeotropic" composition is meant a constant boiling Uquid 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 distiUation of the Uquid has the same composition as the Uquid from which it was evaporated or distiUed, that is, the admixture distiUs/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 "azeotrope-Uke" composition is meant a constant boiling, or substantially constant boiling, Uquid admixture of two or more substances that behaves as a single substance. One way to characterize an azeotrope-Uke composition is that the vapor produced by partial evaporation or distiUation of the Uquid has substantially the same composition as the Uquid from which it was evaporated or distiUed, that is, the admixture distiUs/refluxes without substantial composition change. Another way to characterize an azeotrope-like composition is that the bubble point vapor pressure and the dew point vapor pressure of the composition at a particular temperature are substantially the same.

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 boi :^ 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 HFC-23 and HFC-245cb; HFC-41 and HFC-245cb; HFC- 134a and HFC- 227ca, HFC-227ea or HFC-245cb; HFC-152a and HFC-227ca, HFC-227ea or HFC- 245cb; HFC-227ca and HFC-227ea, HFC-245cb, HFC-263fb, HFC-272ca, or HFC- 281ea; or HFC-227ea and HFC-245cb, HFC-245fa, HFC-254cb, HFC-263fb or HFC-281ea 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 boiUng azeotrope, have boiUng 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 boiUng 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 beUeved 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 foUowing vapor pressures at 25°C.

Component HFC-23 HFC-41 HFC-134a HFC-152a HFC-227ca HFC-227ea HFC-245cb HFC-245fa HFC-254cb HFC-263fb HFC-272ca HFC-281ea

SubstantiaUy constant boiling, azeotropic or azeotrope-like compositions of this invention comprise the following (all compositions are measured at 25°C):

COMPONENTS WEIGHT RANGES PREFERRED

(wt.%/wt/%) (wt.%/wt.%)

HFC-23/HFC-245cb 59-99/1-41 59-99/1-41

HFC-41/HFC-245cb 44-99/1-56 44-99/1-56

HFC-134a/HFC-227ca 1-99/1-99 40-99/1-60

HFC-134a/HFC-227ea 1-99/1-99 40-99/1-60

HFC-134a/HFC-245cb 1-99/1-99 20-99/1-80

HFC-152a/HFC-227ca 1-99/1-99 1-99/1-99

HFC-152a/HFC-227ea 1-99/1-99 1-30/70-99

HFC-152a/HFC-245cb 1-99/1-99 1-99/1-99

HFC-227ca/HFC-227ea 1-99/1-99 1-99/1-99

HFC-227ca/HFC-245cb 1-99/1-99 1-99/1-99

HFC-227ca/HFC-263fb 1-99/1-99 20-99/1-80

HFC-227ca/HFC-272ca 52-99/1-48 50-99/1-50

HFC-227ca/HFC-281ea 1-99/1-99 50-99/1-50

HFC-227ea/HFC-245cb 1-99/1-99 1-99/1-99

HFC-227ea/HFC-245fa 1-33/67-99 1-33/67-99

HFC-227ea/HFC-254cb 1-55/45-99 1-55/45-99

HFC-227ea/HFC-263fb 1-99/1-99 30-99/1-70

HFC-227ea/HFC-281ea 1-99/1-99 50-99/1-50

For purposes of this invention, "effective amount" is defined as the amount of each component of the inventive compositions which, when combined, results in the formation of an azeotropic or azeotrope-Uke composition. This definition includes the amounts of each component, which amounts may vary depending on the pressure appUed to the composition so long as the azeotropic or azeotrope-Uke compositions continue to exist at the different pressures, but with possible different boiUng 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-boiUng 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 weU as those equivalent compositions which are part of the same azeotropic system and are azeotrope-Uke in their properties. As is weU recognized in this art, there is a range of compositions which contain the same components as the azeotrope, which wiU not only exhibit essentially equivalent properties for refrigeration and other appUcations, but which wiU also exhibit essentiaUy 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 boiUng 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 "azeotrope" 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 wiU 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 actuaUty, 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 ^v ?e 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 iUustrating the invention are given below. Unless otherwise stated therein, all percentages are by weight. It is to be understood that these examples are merely iUustrative and in no way are to be interpreted as limiting the scope of the invention.

Impact of Vapor Leakage on Vapor Pressure at 25°C

A vessel is charged with an initial composition at 25°C, and the vapor pressure of the composition is measured. The composition is aUowed to leak from the vessel, whUe 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.

Refrigerant 0 wt% evaporated 50 wt% evaporated 0% change in Composition psia kPa psia kPa vapor pressure

HFC-23/HFC-245cb 93/7 683.5 4713 683.5 4713 0.0

681 678 673 647 596 548 476

592 592 579 557 516 445

466 510 538 557 569 577 583 586 589 590 592

HFC-152a/HFC-245cb 5 91.9/8.1 85.9 592

99/1 85.8 592

60/40 84.5 583

40/60 81.8 564

20/80 76.7 529 0 1/99 68. 469

HFC-227ca/HFC-227ea

46.9/53.1 57.5 396

20/80 60.4 416 5 1/99 66.2 456

70/30 59. 407

85/15 61.2 422

99/1 63.6 439

HFC-227ca/HFC-245cb

43/57 69.9

20/80 69.2

1/99 67.5

70/30 68.8 90/10 66.1

99/1 64.1

HFC-227ca/HFC-263fb

74.9/25.1 67.5 90/10 66.4

99/1 64.2

50/50 65.7

20/80 60.2

1/99 54.4

HFC-227ca/HFC-272ca

97.7/2.3 63.9

99/1 63.8

60/40 57.2 50/50 54.6

52/48 55.1

HFC-227ca/HFC-281ea

88.2/11.8 65.4 99/1 64.1

50/50 60.5

30/70 56.3

20/80 53.7

1/99 47.5

HFC-227ea/HFC-245cb

49.1/50.9 73.1

70/30 72.1

90/10 69.1 99/1 66.9

30/70 72.3

10/90 69.7

1/99 67.7

HFC-227ea/HFC-245fa 4.2/95.8 22.

1/99 22.

30/70 24.6

35/65 26.2

33/67 25.5 176 23. 159 9.8

HFC-227ea/HFC-254cb

0.0 0.6 0.0

7.4

8.6

9.8

10.2

0.0 0.1 0.1 1.4

3.3 3.1 0.4

0.0 0.0 3.6 5.8 6.7

7.7 8.4 8.6 8.6 7.8

5.1 0.6

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 0°C

A leak test is performed on compositions of HFC-227ca and HFC- 272ca, at the temperature of 0°C. The results are summarized below.

These results show that compositions of HFC-227ca and HFC-272ca 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 foUowing table shows the performance of various refrigerants. The data are based on the foUowing conditions.

Evaporator temperature 48.0°F (8.9°C) Condenser temperature 115.0°F (46.1°C) Subcool 12.0°F (6.7°C)

Return gas temperature 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.

Evap. Cond. Capacity

Refrig. Press. Press. Comp. Dis. BTU/min CQ p. Psia fkPa'l Psia (kPa Temp. °F TO £QE (kw)

HCFC-22 95 (655) 258 (1779) 183 (83.9) 4.60 397 (7.0)

HFC-23/HFC-245cb* 5.0/95.0 56(386)

93.0/7.0 163(1124)

95.0/5.0 171(1179)

'Conditions = 80°F/-10°F/12°F/7°F/75%

HFC-41/HFC-245cb 5.0/95.0* 59(407)

94.9/5.1** 127(876)

99.0/1.0** 131(903)

^♦ Conditions = 115 ⁰ F/48°F/12°F/75°F/75% * 'Conditions = 80°F/-10°F/12°F/7°F/75%

HFC-134a/HFC-227ca 1/99 38.9(268)

50/50 52.0(359)

99/1 57.7(398)

HFC-134a/HFC-227ea 1/99 39.7(274)

50/50 53.2(367)

99/1 58.4(403)

HFC-134a/HFC-245cb 5.0/95.0 39(269)

83.3/16.7 57(393)

95.0/5.0 57(393)

HFC-152a/HFC-227ca 1/99 38.9(268)

94.6/5.4 53.4(368)

99/1 53.6(370)

HFC-152a/HFC-227ea 1/99 39.2(274)

50/50 49.9(344)

99/1 52.0(359)

HFC-152a/HFC-245cb 5.0/95.0 41(283)

91.9/8.1 54(372)

95.0/5.0 54(372)

HFC-227ca/HFC-227ea 5.0/95.0 38(262)

46.9/53.1 38(262)

95.0/5.0 38(262)

HFC-227ca/HFC-245cb 5.0/95.0 38(262)

43.0/57.0 39(269)

95.0/5.0 39(269)

HFC-227ca/HFC-263fb 5.0/95.0 33(228)

74.9/25.1 38(262)

95.0/5.0 39(269)

HFC-227ca/HFC-272ca 5.0/95.0 21(145)

97.7/2.3 38(262)

99.0/1.0 38(262)

HFC-227ca/HFC-281ea 5.0/95.0 29(200)

88.2/11.8 40(276)

95.0/5.0 39(269)

HFC-227ea/HFC-245cb 5.0/95.0 38(262)

49.1/50.9 39(269)

95.0/5.0 31(214)

HFC-227ea/HFC-245fa 1.0/99.0 12(83)

4.2/95.8 13(90)

95.0/5.0 28(193)

This Example is directed to measurements of the liquid/vapor equilibrium curves for the mixtures in Figures 1-2, 5, 8-18.

Turning to Figure 1, the upper curve represents the composition of the Uquid, and the lower curve represents the composition of the vapor.

The data for the compositions of the Uquid in Figure 1 are obtained as foUows. A stainless steel cylinder is evacuated, and a weighed amount of HFC-23 is added to the cylinder. The cyUnder is cooled to reduce the vapor pressure of HFC- 23, and then a weighed amount of HFC-245cb is added to the cylinder. The cylinder is agitated to mix the HFC-23 and HFC-245cb, and then the cyUnder 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-23 and HFC-245cb in the cylinder is measured. Additional samples of Uquid are measured the same way, and the results are plotted in Figure 1.

The curve which shows the composition of the vapor is calculated using an ideal gas equation of state.

Vapor/liquid equiUbrium data are obtained in the same way for the mixtures shown in Figures 2, 5, 8-18.

The data in Figures 1, 2, 5, 8, 10-14 and 17-18 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 earUer, 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 Figures 9, 15 and 16 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 vapor pressure compositions are useful in refrigeration, and may show an improved efficiency when compared to the pure components of the composition.

EXAMPLE 6 This Example is directed to measurements of the liquid/vapor equiUbrium curve for mixtures of HFC-134a/HFC-227ca; HFC-134a/HFC-227ea; HFC-152a/HFC-227ca and HFC-152a/HFC-227ea. The Uquid/vapor equiUbrium data for these mixtures are shown in Figures 3, 4, 6 and 7. The upper curve represents the Uquid composition, and the lower curve represents the vapor composition.

The procedure for measuring the composition of the Uquid for mixtures of HFC-134a/HFC-227ca in Figure 3 was as foUows. A stainless steel cylinder was evacuated, and a weighed amount of HFC-134a was added to the cylinder. The cylinder was cooled to reduce the vapor pressure of HFC- 134a, and then a weighed amount of HFC-227ca was added to the cylinder. The cyUnder was agitated to mix the HFC-134a/HFC-227ca, and then the cylinder was placed in a constant temperature bath until the temperature came to equiUbrium at 11.2°C, at which time the vapor pressure of the content of the cyUnder was measured. Samples of the Uquid in the cylinder were taken and analyzed, and the results are plotted in Figure 3 as asterisks, with a best fit curve having been drawn through the asterisks. This procedure was repeated for various mixtures of HFC-134a/HFC- 227ca as indicated in Figure 3. The curve which shows the composition of the vapor is calculated using an ideal gas equation of state.

The procedure for measuring the vapor pressure of mixtures of HFC- 134a/HFC-227ca were carried out in the same w for mixtures of HFC-152a/HFC- 227ea, except that the measurements of the vapoi pressure of mixtures of HFC- 152a/HFC-227ea were taken at -10°C.

The data in Figure 6 show that at 11.2°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 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 Figures 3, 4 and 7 show that although those compositions do not exhibit a maximum or minimum vapor pressure at a particular temperature, they are substantiaUy constant boiling compositions, that is azeotrope-like compositions, because the compositions have dew point vapor pressures and bubble point vapor pressures that are substantially the same at a particular temperature.

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.

The novel compositions of the invention are particularly suitable for replacing refrigerants that may affect the ozone layer, including R-ll, R-12, R-22, R-114 and R-502. In addition to refrigeration applications, the novel constant boiling or substantially constant boiling compositions of the invention are also useful as aerosol propeUants, 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 aUphatic 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 substantiaUy 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 appUcation. Preferred

lubricants include esters having a molecular weight greater than 250.