GB2274462A - Refrigerant composition - Google Patents

Abstract

A refrigerant composition comprising (A) 1,1,2,2,3-pentafluoropropane (R-245ca) and (B) at least one fluorine containing compound selected from the group consisting of the perfluoroalkanes, the hydrofluoroalkanes and the fluorinated alkyl ethers which contain more C-F bonds than C-H and CRC bonds together. The composition may contain a lubricant which comprises at least one polyoocyalkylene glycol compound or an ester base oil which comprises the reaction product of at least one neopentyl polyol and at least one aliphatic carboxylic acid.

Description

REFRIGERANT COMPOSITION The present invention relates generally to refrigerant compositions and in particular to refrigerant compositions which are designed to replace trichlorofluoromethane (Refrigerant R-ll) which is currently used in air conditioning systems.

Heat transfer devices of the mechanical compression type such as refrigerators, freezers, heat pumps and air conditioning systems are well known. In such devices a refrigerant liquid of a suitable boiling point evaporates at low pressure taking heat from a surrounding zone. The resulting vapour is then compressed and passes to a condenser where it condenses and gives off heat to a second zone. The condensate is then returned through an expansion valve to the evaporator so completing the cycle. The mechanical energy required for compressing the vapour and pumping the liquid may be provided by an electric motor or an internal combustion engine.

In addition to having a suitable boiling point and a high latent heat of vaporisation, the properties preferred of a refrigerant include low toxicity, nonflammability, non-corrosivity, high stability and freedom from objectionable odour.

Hitherto, heat transfer devices have tended to use fully and partially halogenated chlorofluorocarbon refrigerants such as trichlorofluoromethane (Refrigerant R-ll), dichlorodifluoromethane (Refrigerant R-12), chlorodifluoromethane (Refrigerant R-22), or the azeotropic mixture of chlorodifluoromethane and chloropentafluoroethane (Refrigerant R-115); the azeotrope being Refrigerant R-502. Refrigerant R-ll, for example, has been widely used in air conditioning systems for office blocks and other large buildings. Air conditioning systems of this type generally comprise a refrigeration unit which operates at pressures close to atmospheric and uses the cooling effect provided by evaporating a suitable refrigerant to chill water which is then circulated around the building.

However, the fully and partially halogenated chlorofluorocarbons have been implicated in the destruction of the earth's protective ozone layer and as a result the use and production thereof is to be severely limited by international agreement.

Whilst heat transfer devices of the type to which the present invention relates are essentially closed systems, loss of refrigerant to the atmosphere can occur due to leakage during operation of the equipment or during maintenance procedures. It is important, therefore, to replace fully and partially halogenated chlorofluorocarbon refrigerants by materials having low or zero ozone depletion potentials.

In addition to the possibility of ozone depletion, it has been suggested that significant concentrations of chlorofluorocarbon refrigerants in the atmosphere might contribute to global warming (the so-called greenhouse effect). It is desirable, therefore, to use refrigerants which have relatively short atmospheric lifetimes as a result of their ability to react with other atmospheric constituents such as hydroxyl radicals.

Replacements for certain of the chlorofluorocarbon refrigerants presently in use have been developed.

These replacement refrigerants tend to comprise selected hydrofluoroalkanes, i.e. compounds which contain only carbon, hydrogen and fluorine atoms in their structure, and both single component and multi-component refrigerants have been developed. Thus, Refrigerant R-12 is generally being replaced by 1,1,1,2-tetrafluoroethane (R-134a). However, there is at present no viable replacement for Refrigerant R-ll.

The present invention provides a refrigerant composition which has a zero ozone depletion potential and which is a viable alternative to Refrigerant R-ll.

According to the present invention there is provided a refrigerant composition comprising: (A) 1,1,2,2,3-pentafluoropropane (R-245ca); and (B) at least one fluorine containing compound selected from the group consisting of the perfluoroalkanes, the hydrofluoroalkanes and the fluorinated alkyl ethers which contain more C-F bonds than C-H and C-C bonds together.

The refrigerant composition of the invention is a mixture comprising 1,1,2,2,3-pentafluoropropane (R-245ca) and at least one compound selected from the group consisting of the perfluoroalkanes, the hydrofluoroalkanes and the fluorinated alkyl ethers.

The perfluoroalkanes, hydrofluoroalkanes and fluorinated alkyl ethers from which component (B) is selected must contain more C-F bonds than C-H and C-C bonds together. The condition on the number of C-F bonds relative to the sum total of C-H and C-C bonds in the perfluoroalkanes, hydrofluoroalkanes and fluorinated alkyl ethers may be stated mathematically as follows: X/ (Y + Z) > 1 wherein X represents the number of C-F bonds in the perfluoroalkane, hydrofluoroalkane or fluorinated alkyl ether; Y represents the number of C-H bonds in the perfluoroalkane, hydrofluoroalkane or fluorinated alkyl ether; and Z represents the number of C-C bonds in the perfluoroalkane, hydrofluoroalkane or fluorinated alkyl ether.

The boiling point and other thermal properties of R-245ca are comparable to R-ll so that. in principle, R-245ca can be used alone as a replacement refrigerant for R-ll. However, R-245ca may become flammable at a temperature of 30 OC and 43 X relative humidity in air.

This flammability problem can be overcome by blending R-245ca with at least one fluorine containing compound as defined above.

The preferred fluorine containing compounds for component (B) have a boiling point of at least 20 OC and more preferably of at least 25 OC, since the refrigerant composition which is formed by blending one or more such compounds with R-245ca is a particularly suitable replacement for refrigerant R-ll.

Component (B) may comprise a single fluorine containing compound or it may comprise a mixture of such compounds.

Preferably, the fluorine containing compounds from which component (B) is selected will contain at least one hydrogen atom in the molecule, since such compounds are more easily destroyed in the lower atmosphere by active radicals such as hydroxyl and, thus, have a shorter atmospheric lifetime. Accordingly, in a preferred embodiment component (B) comprises at least one fluorine containing compound selected from the group consisting of the hydrofluoroalkanes and the partially fluorinated alkyl ethers.

The refrigerant composition of the invention may be an azeotrope, a near azeotrope or it may be zeotropic. Near azeotropic and azeotropic mixtures are preferred, and of these azeotropic mixtures are particularly preferred, since they behave essentially as a single substance. Thus, if the equipment containing such an azeotropic mixture develops a leak, the composition of the material which escapes into the atmosphere and that which remains in the equipment will be essentially the same and will be essentially constant. In short, component fractionation leading to preferential discharge of the higher boiling component(s) of the refrigerant composition is not a problem.This is clearly advantageous, since if the initial refrigerant composition is non-flammable, both the material which escapes into the atmosphere and that which remains in the equipment will be non-flammable and, moreover, will remain non-flammable even when the loss of material to the atmosphere is substantial.

Strictly speaking, of course, a given composition can only be azeotropic at one temperature, and for the purposes of the present invention a composition which is azeotropic at some temperature between the evaporator and condenser temperatures, e.g. midway between the evaporator and condenser temperatures, is especially preferred.

Although the refrigerant composition of the invention is preferably an azeotropic mixture, near-azeotropic mixtures may often exhibit essentially equivalent properties to the true azeotrope and, in particular, may tend not to fractionate to any appreciable extent on boiling. Thus, an initially non-flammable near azeotropic mixture may provide the same advantage as an initially non-flammable true azeotrope.

An especially preferred refrigerant composition is a minimum boiling azeotrope comprising: (A) greater than 50 mole Z, for example from 55 to 95 mole X, of 1,1,2,2,3-pentafluoropropane (R-245ca); and (B) less than 50 mole Z, for example from 45 to 5 mole Z, of at least one compound selected from the group consisting of the perfluoroalkanes, the hydrofluoroalkanes and the fluorinated alkyl ethers which (1) contain more C-F bonds than C-H ~ and C-C bonds together, (2) are less polar than R-245ca and (3) are higher boiling than R-245ca.

One particular advantage of such a minimum boiling azeotrope derives from the greater vapour pressure thereof opposite pure R-245ca, since the refrigeration capacity of a heat transfer device which uses such an azeotrope should be better than one which utilises R-245ca as the sole refrigerant.

Preferred compounds for component (B) are selected from the group consisting of CF3(CF2)3CF3, CF3CF2CF2OCHFCF3, perfluorocyclopentane, CF3CF2CF2CF2CF2H, CF3CF2CF2OCH3, dodecafluorodimethylcyclobutane and perfluorocyclohexane. Of these compounds, CF3(CF2)3CF3, CF3CF2CF2CF2CF2H and CF3CF2CF2OCH3 are preferred since they have the ability to form a minimum boiling azeotrope with R-245ca. CF3CF2CF2CF2CF2H and CF3CF2CF20CH3 are particularly preferred owing to the presence of hydrogen atoms, and CF3CF2CFzOCH3 is especially preferred, since the CH30CF2- moiety should be readily attacked by atmospheric hydroxyl radicals and hence the compound should be readily destroyed in the lower atmosphere if it leaks from the equipment.

In a heat transfer device, the refrigerant is used in combination with a lubricant. The lubricant circulates around the device along with the refrigerant and provides for continual lubrication of the compressor. In addition to possessing good lubricity in the presence of the refrigerant, the properties desired of a lubricant include good hydrolytic stability and good thermal stability. Moreover, in order to provide for the return of the lubricant to the compressor, the lubricant should be compatible with the refrigerant, which in practice means that the lubricant and refrigerant should possess a degree of mutual solubility, i.e. the lubricant and the refrigerant should be at least partially soluble in one another.

Thus, in accordance with a further aspect of the present invention there is provided a refrigerantllubricant composition comprising: (1) a refrigerant composition comprising: (A) 1,1,2,2,3-pentafluoropropane (R-245ca); and (B) at least one fluorine containing compound selected from the group consisting of the perfluoroalkanes, the hydrofluoroalkanes and the fluorinated alkyl ethers which contain more C-F bonds than C-H and C-C bonds together; and (2) sufficient to provide lubrication of a lubricant.

Suitable lubricants include those comprising a polyoxyalkylene glycol base oil. Suitable polyoxyalkylene glycols include hydroxyl group initiated polyoxyalkylene glycols, e.g. ethylene andlor propylene oxide oligomerslpolymers initiated on monoor polyhydric alcohols such as methanol, butanol, pentaerythritol and glycerol. Such polyoxyalkylene glycols may also be end-capped with suitable terminal groups such as alkyl, e.g. methyl groups.

A preferred lubricant of the type comprising a polyoxyalkylene glycol base oil is one which comprises at least one polyoxyalkylene glycol having the general formula: A [-O-(CH2CH(CH3)O)l(CH2CH2O)m - Q]x I wherein A is the residue remaining after removing the hydroxyl groups from a hydroxyl containing organic compound; Q represents an optionally substituted alkyl, aralkyl or aryl group; 1 and m are independently 0 or an integer provided that at least one of 1 or m is an integer; and x is an integer, said at least one polyoxyalkylene glycol having an average molecular weight in the range of from about 150 to about 3000.

Polyoxyalkylene glycols of Formula I may be prepared using conventional techniques. Such techniques are well known to those skilled in the art. Thus, in one method a hydroxyl containing organic compound such as an alcohol is reacted with ethylene oxide and/or propylene oxide to form an ethylene oxide and/or propylene oxide oligomerlpolymer containing terminal hydroxyl groups which is subsequently etherified to give a product comprising a polyoxyalkylene glycol of Formula I. The product which is finally formed will not usually consist of a single polyoxyalkylene glycol of Formula I, but will usually comprise a mixture of such compounds which vary from one another in respect of the degree of polymerisation, i.e. the number of ethylene and/or propylene oxide residues.Moreover, a mixture of alcohols andlor phenols may be used as initiators in the formation of the polyoxyalkylene glycol, and a mixture of etherifying agents which provide different Q groups may also be used. In the usual case where the product comprises a mixture of polyoxyalkylene glycols of Formula I, it is the average molecular weight of all the glycols present which is important, so that the product may contain specific glycols which have a molecular weight outside the range quoted above, providing that the average molecular weight of all the glycols present is within that range.

The moiety A in the polyoxyalkylene glycol of Formula I is the residue remaining after removing the hydroxyl groups from a hydroxyl containing organic compound. Such compounds include the mono- and polyhydric alcohols and phenols. Where the hydroxyl containing organic compound which is used as an initiator in the formation of the polyoxyalkylene glycol is a monohydric alcohol or phenol, A is preferably a hydrocarbyl group and more preferably is an alkyl, aryl, alkaryl or aralkyl group, especially alkyl. Suitable alkyl groups for A may be selected from the straight chain (linear), branched or cyclic alkyl groups. Preferably, A is a C112, particularly a C1-10 and especially a C16 alkyl group. Specific examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, the various pentyl groups, the various hexyl groups, cyclopentyl, cyclohexyl and the like. Particularly preferred alkyl groups for A are the C112, particularly the C1-10 and especially the C16 straight chain alkyl groups, examples of which have been listed above. An especially preferred alkyl group for A is methyl or n-butyl.

Other suitable hydrocarbyl groups for A are those which remain after removing a hydroxyl group(s) from benzyl alcohol and phenols such as phenol, cresol, nonylphenol, resorcinol and bisphenol A.

Where a polyhydric alcohol is used in the formation of the polyoxyalkylene glycol, A is preferably a hydrocarbon radical. Suitable hydrocarbon radicals for A are those which remain after removing the hydroxyl groups from polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, l, & hexanediol, diethylene glycol1 dipropylene glycol, cyclohexane dimethanol, glycerol, 1,2,6-hexane triol, trimethylolpropane, pentaerythritol, dipentaerythritol and sorbitol. A particularly preferred hydrocarbon radical for A is that which remains after removing the hydroxyl groups from glycerol.

The moiety Q in the polyoxyalkylene glycol of Formula I is an optionally substituted alkyl, aralkyl or aryl group. A preferred optionally substituted aralkyl group for Q is an optionally substituted benzyl group. Preferred optionally substituted aryl groups for Q include phenyl and alkyl substituted phenyl groups.

Preferably, Q is an optionally substituted, for example halogen substituted, alkyl group, particularly an optionally substituted C1-12 alkyl group and more particularly an optionally substituted C14 alkyl group. Suitable alkyl groups for Q may be selected from the straight chain (linear), branched or cyclic alkyl groups, especially the linear alkyl groups. Although the alkyl groups for Q are described as being optionally substituted, they are preferably unsubstituted. Accordingly, particularly preferred alkyl groups for Q are selected from methyl, ethyl, propyl, isopropyl and the various butyl groups. An especially preferred alkyl group for Q is methyl.

The polyoxyalkylene glycol of Formula I may be a polyoxyethylene glycol, a polyoxypropylene glycol or a poly(oxyethylene/oxypropylene) glycol. In the latter case, the ethylene and propylene oxide residues may be arranged randomly or in blocks along the polymer chain.

Preferred polyoxyalkylene glycols are the polyoxypropylene glycols and the poly(oxyethylene/oxypropylene) glycols.

Preferred lubricants are those comprising an ester base oil which comprises at least one neopentyl polyol ester derived from the reaction of at least one neopentyl polyol and at least one aliphatic carboxylic acid or an esterifiable derivative thereof. The preference for these lubricants is due, inter alia, to their generally high level of thermal stability.

Suitable neopentyl polyols for the formation of the ester base oil include pentaerythritol, polypentaerythritols such as di- and tripentaerythritol, trimethylol alkanes such as trimethylol ethane and trimethylol propane, and neopentyl glycol. The esters may be formed with linear and/or branched aliphatic carboxylic acids, such as linear andlor branched alkanoic acids. A minor proportion of an aliphatic polycarboxylic acid, e.g. an aliphatic dicarboxylic acid, may also be used in the synthesis of the ester in order to increase the viscosity thereof. However, where such an aliphatic polycarboxylic acid is employed in the synthesis, it will preferably constitute no more than 30 mole Z, more preferably no more than 10 mole Z of the carboxylic acids used in the synthesis.Usually, the amount of the carboxylic acid(s) which is used in the synthesis will be sufficient to esterify all of the hydroxyl groups contained in the polyol, although residual hydroxyl functionality may be acceptable. It will be appreciated that esterifiable derivatives of carboxylic acids may be used in the synthesis if desired.

A preferred lubricant for use in the refrigerantilubricant composition of the invention is one in which the ester base oil comprises the reaction product of at least one neopentyl polyol selected from neopentyl glycol, trimethylol propane, pentaerythritol and dipentaerythritol, especially at least one nespentyl polyol selected from trimethylol propane, pentaerythritol and dipentaerythritol, and at least one aliphatic carboxylic acid selected from the straight chain (linear) aliphatic carboxylic acids and the branched aliphatic carboxylic acids.As indicated above, esterifiable derivatives of the carboxylic acids may also be used in the synthesis, such as the acyl halides, anhydrides and lower alkyl esters thereof, and hereinafter whenever reference is made to the use of carboxylic acids in the synthesis of the ester base oil the use of esterifiable derivatives thereof is not to be excluded. Suitable acyl halides are the acyl chlorides and suitable lower alkyl esters are the methyl esters.

The base oil in this preferred lubricant comprises one or more ester compounds of formula:

wherein R is the hydrocarbon radical remaining after removing the hydroxyl groups from neopentyl glycol, trimethylol propane, pentaerythritol or dipentaerythritol, especially the hydrocarbon radical remaining after removing the hydroxyl groups from trimethylol propane, pentaerythritol or dipentaerythritol each R1 is, independently, a straight chain (linear) aliphatic hydrocarbyl group or a branched aliphatic hydrocarbyl group; and n is an integer of 2, 3, 4, or 6.

The aliphatic hydrocarbyl groups specified for R1 above may be substituted, e.g. by pendant atoms or groups such as chloro, fluoro and bromo, and/or by in chain hetero atoms such as oxygen and nitrogen.

Preferably, however, such hydrocarbyl groups are unsubstituted and thus contain only carbon and hydrogen atoms.

It will be appreciated that a suitable base oil may comprise a single ester compound of Formula II, i.e. the product which is formed from the reaction of a single neopentyl polyol and a single carboxylic acid.

Alternatively, a suitable base oil may comprise two or more compounds of Formula II. Such a base oil may be prepared by utilising two or more neopentyl polyols and/or two or more carboxylic acids in the synthesis of the ester, or by combining a mixture of different ester compounds each of which is the reaction product of a particular neopentyl polyol and a particular carboxylic acid. Furthermore, different mixed ester compositions, each of which has been prepared by utilising two or more neopentyl polyols and! our two or more carboxylic acids in their synthesis, may also be blended together to form the ester base oil.

A preferred ester base oil comprises one or more compounds of Formula II in which each R1 is, independently, a linear alkyl group or a branched alkyl group.

Preferred linear alkyl groups for R1 are the C49 linear alkyl groups, and ester compounds containing such alkyl groups can be prepared by using at least one Cg-10 linear alkanoic acid selected from pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid and decanoic acid in the synthesis of the ester base oil. Particularly preferred linear alkyl groups for Rl are the C48 linear alkyl groups, especially the linear C4 and linear C6 alkyl groups which are derived from pentanoic and heptanoic acids respectively. The linear C6 alkyl group is an especially preferred linear alkyl group.

Preferred branched alkyl groups for R1 are the C6g branched alkyl groups, and ester compounds containing such alkyl groups can be prepared by using at least one C7-10 branched alkanoic acid in the synthesis of the ester base oil, such as 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 2,2-dimethylpentanoic acid, 2,4-dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 2-ethylhexanoic acid, 3,5-dimethylhexanoic acid, 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid, 2,2-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 2-methyloctanoic acid, 3-methyloctanoic acid, 2-ethylheptanoic acid and isodecanoic acid.Particularly preferred branched alkyl groups for R1 are the C79 branched alkyl groups, especially the branched C8 alkyl groups which are derived from branched Cg alkanoic acids.

A particularly preferred ester base oil is obtained when a combination of linear and branched alkanoic acids are used in the synthesis thereof so that the oil comprises one or more compounds of Formula II in which at least a proportion of the R1 groups are linear alkyl groups and at least a proportion of the R1 groups are branched alkyl groups.

Where a mixture of linear and branched alkanoic acids are utilised in the synthesis of the ester base oil, as is preferred, the linear alkanoic acid(s) preferably constitutes at least 20 mole Z, e.g from 20 to 80 mole Z, of the total amount of carboxylic acids used. In this way, at least 20 mole Z, e.g. from 20 to 80 mole Z, of the hydroxyl groups contained in the polyol or mixture of polyols may be reacted with the said linear alkanoic acid(s).

Typically, the lubricant will also comprise one or more of the additives which are conventional in the refrigeration lubricants art. Specific mention may be made of antioxidants, deacidifying agents, anti-wear agents and extreme pressure resistance agents. Such additives are well known to those skilled in the art.

Where the lubricant comprises such additives, they may be present in the amounts conventional in the art.

Preferably, the cumulative weight of all the additives will not be more than 8 Z, e.g. 5 Z, of the total weight of the lubricant.

Preferred antioxidants are the compounds containing a hindered phenol in the molecule, preferred deacidifying agents are the compounds containing an epoxy group in the molecule, and the preferred anti-wear and extreme pressure resistance agents are the organophosphorous compounds, particularly the organo phosphates, phosphites and thiophosphates.

The following compounds are representative of the preferred antioxidants, deacidifying agents, anti-wear agents and extreme pressure resistance agents.

Antioxidants: 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-hydroxyphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'methylenebis(4-ethyl-6-t-butylphenol), 2,2'-butylidenebis(4-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4- hydroxybenzyl)benzene and the like.

Deacidifying agents: Phenyl glycidyl ether, butylglycidyl ether, bisphenol A epichlorohydrin condensate, vinylcyclohexene dioxide, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxycyclohexane) meta-dioxane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, polypropylene glycol diglycidyl ether, resorcin diglycidyl ether, polyethylene glycol diglycidyl ether and the like.

Anti-wear and extreme pressure resistance agents: Tricresyl phosphate, trisnonylphenylphosphite, distearyl phosphate, tributylphosphate, trilaurylphosphate, trilaurylphosphite, mono-di-mixed-lauryl phosphite, mono-di-mixed-tridecyl phosphate, mono-2-ethylhexyl- 2-ethylhexylphosphate, di-2-ethylhexyl phosphate and the like.

The refrigerantllubricant compositions of the invention will typically comprise a major amount of the refrigerant and a minor amount of the synthetic lubricant. Preferably, the refrigerant/lubricant compositions of the invention will comprise from 50 to 99 Z by weight, more preferably from 70 to 99 Z by weight, of the refrigerant and from 1 to 50 Z by weight, more preferably from 1 to 30 Z by weight, of the lubricant based on the total weight thereof.

The refrigerant and refrigerantllubricant compositions of the invention provide a good compromise between performance and zero ozone depletion. They are especially suitable for air conditioning applications currently satisfied by working fluid compositions based on refrigerant R-ll.

Claims (14)

Claims:

1. A refrigerant composition comprising: (A) 1,1,2,2,3-pentafluoropropane (R-245ca); and (B) at least one fluorine containing compound selected from the group consisting of the perfluoroalkanes, the hydrofluoroalkanes and the fluorinated alkyl ethers which contain more C-F bonds than C-H and C-C bonds together.

2. A refrigerant composition as claimed in claim 1 wherein the at least one fluorine containing compound making up component (B) has a boiling point of at least 200C.

3.~ A refrigerant composition as claimed in claim 1 wherein component (B) comprises at least one fluorine containing compound selected from the hydrofluoroalkanes and the partially fluorinated alkyl ethers.

4. A refrigerant composition as claimed in claim 1 wherein component (B) comprises at least one fluorine containing compound selected from the group consisting of CF3(CF2)3CF3, CF3CF2CF2OCHFCF3, perfluorocyclopentane, CF3CF2CF2CF2CF2H, CF3CF2CF2OCH3, dodecafluorodimethylcyclobutane and perfluorocyclohexane.

5. A refrigerant composition as claimed in claim 4 wherein component (B) comprises at least one fluorine containing compound selected from the group consisting of CF3(CF2)3CF3, CF3CF2CF2CF2CF2H and CF3CF2CF2OCH3.

6. A refrigerant composition as claimed in claim 5 wherein component (B) comprises at least one fluorine containing compound selected from the group consisting of CF3CF2CF2CF2CF2H and CF3CF2CF2OCH3.

7. A refrigerant composition as claimed in any one of claims 1 to 6 characterised in that it is an azeotrope or near azeotrope.

8. A refrigerant composition as claimed in claim 7 characterised in that it forms an azeotrope at a temperature between the evaporator and condenser temperatures.

9. A refrigerant composition comprising: (A) greater than 50 mole Z of 1,1,2,2,3-pentafluoropropane (R-245ca); and (B) less than 50 mole Z of at least one fluorine containing compound selected from the group consisting of the perfluoroalkanes, the hydrofluoroalkanes and the fluorinated alkyl ethers which (1) contain more C-F bonds than C-H and C-C bonds together, (2) are less polar than R-245ca and (3) are higher boiling than R-245ca.

10. A refrigerant composition as claimed in claim 9 wherein component (B) comprises at least one fluorine containing compound selected from the group consisting of CF3(CF2)3CF3, CF3CF2CF2CF2CF2H and CF3CF2CFzOCH3.

11. A refrigerant composition as claimed in claim 10 wherein component (B) comprises at least one fluorine containing compound selected from the group consisting of CF3CF2CF2CF2CF2H and CF3CF2CF2OCH3.

12. A refrigerant/lubricant composition comprising: (1) a refrigerant composition as claimed in any one of claims 1 to 11; and (2) sufficient to provide lubrication of a lubricant.

13. A refrigerant/lubricant composition as claimed in claim 12 wherein the lubricant comprises a base oil which comprises at least one polyoxyalkylene glycol compound.

14. A refrigerantllubricant composition as claimed in claim 12 wherein the lubricant comprises an ester base oil which comprises the reaction product of at least one neopentyl polyol and at least one aliphatic carboxylic acid or an esterifiable derivative thereof.