WO2014128442A2 - Heat transfer compositions - Google Patents

Abstract

The invention provides a comprising 1,2,3,3,3-pentafIuoropropene (R-1225ye), 1,1,1,2- tetrafluoroethane (R-134a) and from about 3 to about 25 % by weight carbon dioxide (C02, R-744). Also provided is a composition comprising R-1225ye, carbon dioxide and 1,3,3,3-tetrafluoropropene (R-1234ze). Further provided is a composition comprising from about 6 to about 28 % by weight carbon dioxide and from about 72 to about 96 % by weight R-1225ye.

Description

HEAT TRANSFER COMPOSITIONS

The invention relates to heat transfer compositions, and in particular to heat transfer compositions which may be suitable as replacements for existing refrigerants such as R- 134a, R-152a, R-1234yf, R-22, R-410A, R-407A, R-407B, R-407C, R507 and R-404a.

The listing or discussion of a prior-published document or any background in the specification should not necessarily be taken as an acknowledgement that a document or background is part of the state of the art or is common general knowledge.

Mechanical refrigeration systems and related heat transfer devices such as heat pumps and air-conditioning systems are well known. In such systems, a refrigerant liquid evaporates at low pressure taking heat from the surrounding zone. The resulting vapour is then compressed and passed to a condenser where it condenses and gives off heat to a second zone, the condensate being returned through an expansion valve to the evaporator, so completing the cycle. Mechanical energy required for compressing the vapour and pumping the liquid is provided by, for example, 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 in a refrigerant include low toxicity, non-flammability, non-corrosivity, high stability and freedom from objectionable odour. Other desirable properties are ready compressibility at pressures below 25 bars, low discharge temperature on compression, high refrigeration capacity, high efficiency (high coefficient of performance) and an evaporator pressure in excess of 1 bar at the desired evaporation temperature.

Dichlorodifluoromethane (refrigerant R-12) possesses a suitable combination of properties and was for many years the most widely used refrigerant. Due to international concern that fully and partially halogenated chlorofluorocarbons were damaging the earth's protective ozone layer, there was general agreement that their manufacture and use should be severely restricted and eventually phased out completely. The use of dichlorodifluoromethane was phased out in the 1990's.

Chlorodifluoromethane (R-22) was introduced as a replacement for R-12 because of its lower ozone depletion potential. Following concerns that R-22 is a potent greenhouse gas, its use is also being phased out. 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 zero ozone depletion potentials.

In addition to the possibility of ozone depletion, it has been suggested that significant concentrations of halocarbon 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, or as a result of ready degradation through photolytic processes. R-410A and R-407 refrigerants (including R-407A, R-407B and R-407C) have been introduced as a replacement refrigerant for R-22. However, R-22, R-410A and the R-407 refrigerants all have a high global warming potential (GWP, also known as greenhouse warming potential). 1 ,1 ,1 ,2-tetrafluoroethane (refrigerant R-134a) was introduced as a replacement refrigerant for R-12. R-134a is an energy efficient refrigerant, used currently for automotive air conditioning. However it is a greenhouse gas with a GWP of 1430 relative to CO2 (GWP of CO2 is 1 by definition). The proportion of the overall environmental impact of automotive air conditioning systems using this gas, which may be attributed to the direct emission of the refrigerant, is typically in the range 10-20%. Legislation has been passed in the European Union to rule out use of refrigerants having GWP of greater than 150 for new models of car. The car industry operates global technology platforms, and in any event emission of greenhouse gas has global impact, thus there is a need to find fluids having reduced environmental impact (e.g. reduced GWP) compared to HFC-134a.

R-152a (1 ,1-difluoroethane) has been identified as an alternative to R-134a. It is somewhat more efficient than R-134a and has a greenhouse warming potential of 120. However the flammability of R-152a is judged too high, for example to permit its safe use in mobile air conditioning systems. In particular it is believed that its lower flammable limit in air is too low, its flame speeds are too high, and its ignition energy is too low. Thus there is a need to provide alternative refrigerants having improved properties such as low flammability.

There is also a need to provide alternative refrigerants that may be used in existing devices such as refrigeration devices with little or no modification.

R-1234yf (2,3,3,3-tetrafluoropropene) has been identified as a candidate alternative refrigerant to replace R-134a in certain applications, notably the mobile air conditioning or heat pumping applications. Its GWP is about 4. R-1234yf is flammable and its flammability characteristics are regarded in some quarters as not being acceptable for certain applications such as mobile air conditioning.

The environmental impact of operating an air conditioning or refrigeration system, in terms of the emissions of greenhouse gases, should be considered with reference not only to the so-called "direct" GWP of the refrigerant, but also with reference to the so- called "indirect" emissions, meaning those emissions of carbon dioxide resulting from consumption of electricity or fuel to operate the system. Several metrics of this total GWP impact have been developed, including those known as Total Equivalent Warming Impact (TEWI) analysis, or Life-Cycle Carbon Production (LCCP) analysis. Both of these measures include estimation of the effect of refrigerant GWP and energy efficiency on overall warming impact. Emissions of carbon dioxide associated with manufacture of the refrigerant and system equipment should also be considered.

The energy efficiency and refrigeration capacity of R-1234yf have been found to be significantly lower than those of R-134a and in addition the fluid has been found to exhibit increased pressure drop in system pipework and heat exchangers. A consequence of this is that to use R-1234yf and achieve energy efficiency and cooling performance equivalent to R-134a, increased complexity of equipment and increased size of pipework is required, leading to an increase in indirect emissions associated with equipment. Furthermore, the production of R-1234yf is thought to be more complex and less efficient in its use of raw materials (fluorinated and chlorinated) than R-134a. Current projections of long term pricing for R-1234yf is in the range 10-20 times greater than R-134a. This price differential and the need for extra expenditure on hardware will limit the rate at which refrigerants are changed and hence limit the rate at which the overall environmental impact of refrigeration or air conditioning may be reduced. In summary, the adoption of R-1234yf to replace R-134a wilt consume more raw materials and result in more indirect emissions of greenhouse gases than does R-134a.

A principal object of the present invention is therefore to provide a heat transfer composition which is usable in its own right or suitable as a replacement for existing refrigeration usages which should have a reduced GWP, yet have a capacity and energy efficiency (which may be conveniently expressed as the "Coefficient of Performance") ideally within 10% of the values, for example of those attained using existing refrigerants (e.g. R-134a, R-152a, R-1234yf, R-22, R-410A, R-407A, R-407B, R-407C, R507 and R- 404a), and preferably within less than 10% (e.g. about 5%) of these values. It is known in the art that differences of this order between fluids are usually resolvable by redesign of equipment and system operational features. The composition should also ideally have acceptable toxicity and acceptable flammability. The subject invention addresses the above deficiencies by the provision of certain compositions based on 1 ,2,3,3,3-pentafluoropropene (R-1225ye) and carbon dioxide (C0₂, R-744).

In one embodiment, the subject invention provides a heat transfer composition comprising 1 ,2,3,3,3-pentafluoropropene (R-1225ye), 1 ,1 ,1 ,2-tetrafluoroethane (R-134a) and from about 3 to about 25 % by weight carbon dioxide (C0₂, R-744). Unless otherwise stated, these compositions will be referred to herein as the R-1225ye/CC>2/R- 134a compositions of the invention. Preferably, the R-1225ye/C0₂/R-134a compositions of the invention contain from about 3 to about 20 % by weight C0₂, for example from about 4 to about 18 % by weight. In one aspect, the R-1225ye/C0₂/R-134a compositions of the invention contain from about 4 to about 16 % by weight CO2, such as from about 4 to about 12 or 14 % by weight. Advantageously, the R-1225ye/C02/R-134a compositions of the invention contain at least about 50 % by weight R-1225ye, for example from about 60 to about 95 % by weight. In one aspect, the R-1225ye/C02/R-134a compositions of the invention contain from about 70 to about 92 % by weight R-1225ye. In a preferred embodiment, the R-1225ye/C02/R-134a compositions of the invention contain up to about 40 % by weight R-134a, for example from about 2 to about 30 % by weight. In one aspect, the R-1225ye/C02/R-134a compositions of the invention contain from about 3 to about 20 % by weight R-134a, such as from about 4 to about 15 % by weight. Certain preferred R-1225ye/C0₂/R-134a compositions of the invention comprise from about 55 to about 95 % by weight R- 225ye, from about 2 to about 20 % by weight R- 134a and from about 3 to about 18 % by weight C0₂. Further preferred R- 1225ye/C0₂/R-134a compositions of the invention comprise from about 70 to about 93 % by weight R-1225ye, from about 3 to about 12 % by weight R-134a and from about 3 to about 16 % by weight C0₂.

In another embodiment, the subject invention provides a heat transfer composition comprising 1 ,2,3,3,3-pentafluoropropene (R-1225ye), 1 ,3,3,3-tetrafluoropropene (R- 1234ze) and carbon dioxide (C0_2l R-744). Unless otherwise stated, these compositions will be referred to herein as the R-1225ye/C0₂/R-1234ze compositions of the invention.

Preferably, the R-1225ye/C0₂/R-1234ze compositions of the invention contain up to about 30 % by weight C0₂, for example from about 2 to about 25 % by weight. In one aspect, the R-1225ye/C0₂/R-1234ze compositions of the invention contain from about 3 to about 20 % by weight C0₂, such as from about 4 to about 14 or 16 % by weight.

Advantageously, the R-1225ye/C0₂/R-1234ze compositions of the invention contain up to about 90 % by weight R-1225ye, for example from about 2 to about 85 % by weight. In one aspect, the R-1225ye/C0₂/R-1234ze compositions of the invention contain from about 3 to about 70 % by weight R-1225ye.

In a preferred embodiment, the R-1225ye/C0₂/R-1234ze compositions of the invention contain up to about 95 % by weight R-1234ze, for example from about 2 to about 92 % by weight. In one aspect, the R-1225ye/C0₂/R-1234ze compositions of the invention contain from about 5 to about 90 % by weight R-1234ze, such as from about 10 to about 88 % by weight.

Certain preferred R-1225ye/C0₂/R-1234ze compositions of the invention comprise from about 4 to about 80 % by weight R-1225ye, from about 2 to about 20 % by weight R-C0₂ and from about 10 to about 94 % by weight R-1234ze. Further preferred R- 1225ye/C0₂/R-1234ze compositions of the invention comprise from about 4 to about 70 % by weight R-1225ye, from about 2 to about 15 % by weight C0₂ and from about 20 to about 92 % by weight R-1234ze.

In a preferred aspect, the R-1225ye/C(_>2/R-1234ze compositions of the invention additionally contain R-134a, for example up to about 30 % by weight R-134a. Unless otherwise stated, these compositions will be referred to herein as the R-1225ye/C02/R- 1234ze/R-134a compositions of the invention.

Preferred R-1225ye/CC>2/R-1234ze/R-134a compositions of the invention comprise from about 4 to about 85 % by weight R-1225ye, from about 2 to about 20 % by weight C0₂, from about 4 to about 85 % by weight R-1234ze and from about 2 to about 20 % by weight R-134a.

Advantageously, the R-1225ye/C0₂/R-1234ze/R-134a compositions of the invention comprise from about 5 to about 80 % by weight R-1225ye, from about 3 to about 15 % by weight C0₂, from about 5 to about 80 % by weight R-1234ze and from about 3 to about 15 % by weight R-134a.

Further preferred R-1225ye/C02/R-1234ze/R-134a compositions of the invention comprise from about 10 to about 80 % by weight R-1225ye, from about 4 to about 14 % by weight CO2, from about 10 to about 80 % by weight R-1234ze and from about 3 to about 12 % by weight R-134a.

In another embodiment of the subject invention provides a heat transfer composition comprising from about 72 to about 94 % by weight 1 ,2,3,3,3-pentafluoropropene (R- 1225ye) and from about 6 to about 28 % by weight carbon dioxide (CO2, R-744). Unless otherwise stated, these compositions will be referred to herein as the R-1225ye/C0₂ compositions of the invention. Preferably, R-1225ye/C02 compositions of the invention contain from about 75 to about 94 % by weight R-1225ye and from about 6 to about 25 % by weight C0₂. Further preferred R-1225ye/C02 compositions of the invention contain from about 80 to about 94 % by weight R-1225ye and from about 6 to about 20 % by weight C0₂. Advantageously, the R-1225ye/C02 compositions of the invention contain from about 84 to about 94 % by weight R-1225ye and from about 6 to about 16 % by weight C0_2> for example from about 86 to about 93 % by weight R-1225ye and from about 7 to about 14 % by weight C0₂.

All of the chemicals herein described are commercially available. For example, the fluorochemicals may be obtained from Apollo Scientific (UK).

As used herein, all % amounts mentioned in compositions herein, including in the claims, are by weight based on the total weight of the compositions, unless otherwise stated. By the term "about", as used in connection with numerical values of amounts of components in % by weight, we include the meaning of ± 0.5 % by weight.

For the avoidance of doubt, it is to be understood that the stated upper and lower values for ranges of amounts of components in the compositions of the invention described herein may be interchanged in any way, provided that the resulting ranges fall within the broadest scope of the invention.

R-1225ye exists in two geometric isomers, c/s-1 ,2,3,3,3-pentafluoropropene (R- 1225ye(Z)) and trans- ,2,3,3,3-pentafluoropropene (R-1225ye(Z)). Preferably, the compositions of the invention described herein contain R-1225ye(Z). In one aspect, as used herein, R-1225ye refers to R-1225ye(Z).

R-1234ze exists in two geometric isomers, c/^'s-1 ,3,3,3-tetrafluoropropene (R-1234ze(Z)) and trans- ,3,3,3-tetrafluoropropene (R-1234ze(E)). Preferably, the R-1225ye/C0₂/R- 1234ze and R-1225ye/C0₂/R-1234ze/R-134a compositions of the invention described herein contain R-1234ze(E). In one aspect, as used herein, R-1234ze refers to R- 1234ze(E).

In a preferred embodiment, the compositions of the invention are substantially free of any other component that has heat transfer properties.

In one aspect, the compositions of the invention are substantially free of (i) any other hydrofluorocarbon compound (other than R-1225ye, R-1234ze and R-134a), and/or (ii) any hydrocarbon. Any of the compositions of the invention described herein, including those with specifically defined amounts of R-1225ye, CO2 R-1234ze(E) and R-134a, may consist essentially of (or consist of) the amounts of R-1225ye, C0₂ R-1234ze(E) and R-134a defined in those compositions.

By the term "consist essentially of, we include the meaning that the compositions of the invention contain substantially no other components, particularly no further hydrofluorocarbon compounds known to be used in heat transfer compositions (e.g. hydrofluoroalkanes, hydrofluoroalkenes or hydrocarbons). We include the term "consist of within the meaning of "consist essentially of.

Compositions according to the invention conveniently comprise substantially no R- 1225zc (1 ,1 ,3,3,3-pentafluoropropene). By "substantially no" and "substantially free of, we include the meaning that the compositions of the invention contain 0.5% by weight or less of the stated component, preferably 0.1% or less, based on the total weight of the composition.

Certain compositions of the invention may contain substantially no:

(i) 2,3,3,3-tetrafluoropropene (R-1234yf),

(ii) R-1234ze(Z),

(iii) R-1225ye(E)

(iv) difluoromethane (R-32);

(v) 1 ,1-difluoroethane (R-152a);

(vi) pentafluoroethance (R125); and/or

(vii) 3,3,3-trifluoropropene (R-1243zf).

The compositions of the invention have zero ozone depletion potential. Typically, the compositions of the invention have a GWP of less than about 1000, such as less than about 800. In one embodiment, the compositions of the invention have a GWP of less than about 500, for example, less than about 400. Preferably, the compositions of the invention have a GWP of less than about 300 or 200. Advantageously, the compositions of the invention have a GWP of less than about 150, e.g. less than about 100, or even as low as less than about 50. Preferably, compositions of the invention are non-flammable at a test temperature of 60°C using the ASHRAE-34 methodology. Advantageously, the mixtures of vapour that exist in equilibrium with the compositions of the invention at any temperature between about -20°C and 60°C are also non-flammable.

In an embodiment, the compositions are of reduced flammability hazard when compared to R-1234ze(E) alone or R-1234yf alone.

Flammability may be determined in accordance with ASHRAE Standard 34 incorporating the ASTM Standard E-681 with test methodology as per Addendum 34p dated 2004, the entire content of which is incorporated herein by reference.

In one aspect, the compositions have one or more of (a) a higher lower flammable limit; (b) a higher ignition energy (sometimes referred to as auto ignition energy or pyrolysis); or (c) a lower flame velocity compared to R-1234ze(E) alone or R-1234yf alone. In a preferred embodiment, the compositions of the invention are non-flammable. Advantageously, the mixtures of vapour that exist in equilibrium with the compositions of the invention at any temperature between about -20°C and 60°C are also nonflammable.

Preferably, the compositions of the invention are less flammable compared to R- 1234ze(E) or R-1234yf in one or more of the following respects: lower flammable limit at 23°C; lower flammable limit at 60°C; breadth of flammable range at 23°C or 60°C; auto- ignition temperature (thermal decomposition temperature); minimum ignition energy in dry air or flame speed. The flammable limits being determined according to the methods specified in ASHRAE-34 and the auto-ignition temperature being determined in a 500ml glass flask by the method of ASTM E659-78.

In some applications it may not be necessary for the formulation to be classed as non- flammable by the ASHRAE-34 methodology; it is possible to develop fluids whose flammability limits will be sufficiently reduced in air to render them safe for use in the application, for example if it is physically not possible to make a flammable mixture by leaking the refrigeration equipment charge into the surrounds. The critical temperature of a heat transfer composition should be higher than the maximum expected condenser temperature. This is because the cycle efficiency drops as critical temperature is approached. As this happens, the latent heat of the refrigerant is reduced and so more of the heat rejection in the condenser takes place by cooling gaseous refrigerant; this requires more area per unit heat transferred. R-410A is commonly used in building and domestic heat pump systems and by way of illustration its critical temperature of about 71 °C is higher than the highest normal condensing temperature required to deliver useful warm air at about 50 °C. The automotive duty requires air at about 50 °C so the critical temperature of the fluids of the invention should be higher than this if a conventional vapour compression cycle is to be utilised. Critical temperature is preferably at least 15K higher than the maximum air temperature.

In one aspect, the compositions of the invention have a critical temperature of greater than about 65 °C, preferably greater than about 70 °C.

It is believed that the compositions of the invention exhibit a completely unexpected combination of low-/non-flammability, low GWP and improved refrigeration performance properties. Some of these refrigeration performance properties are explained in more detail below.

Advantageously, the volumetric refrigeration capacity of the compositions of the invention is at least 80% of the existing refrigerant fluid it is replacing, preferably at least 85%, 90% or even at least 95%. The compositions of the invention typically have a volumetric refrigeration capacity that is at least 90% of that of R-1234yf. Preferably, the compositions of the invention have a volumetric refrigeration capacity that is at least 95% of that of R-1234yf, for example from about 95% to about 120% of that of R-1234yf. In one embodiment, the cycle efficiency (Coefficient of Performance, COP) of the compositions of the invention is within about 5% or even better than the existing refrigerant fluid it is replacing

Conveniently, the compressor discharge temperature of the compositions of the invention is within about 15K of the existing refrigerant fluid it is replacing, preferably about 10K or even about 5K. The compositions of the invention preferably have energy efficiency at least 95% (preferably at least 98%) of R-134a under equivalent conditions, while having reduced or equivalent pressure drop characteristics and cooling capacity at 95% or higher of R-134a values. Advantageously the compositions have higher energy efficiency and lower pressure drop characteristics than R-134a under equivalent conditions. The compositions also advantageously have better energy efficiency and pressure drop characteristics than R-1234yf alone. The heat transfer compositions of the invention are suitable for use in existing designs of equipment, and are compatible with all classes of lubricant currently used with established HFC refrigerants. They may be optionally stabilized or compatibilized with mineral oils by the use of appropriate additives. Preferably, when used in heat transfer equipment, the composition of the invention is combined with a lubricant.

Conveniently, the lubricant is selected from the group consisting of mineral oil, silicone oil, polyalkyl benzenes (PABs), polyol esters (POEs), polyalkylene glycols (PAGs), polyalkylene glycol esters (PAG esters), polyvinyl ethers (PVEs), poly (alpha-olefins) and combinations thereof. PAGs and POEs are currently preferred lubricants for the compositions of the invention.

Advantageously, the lubricant further comprises a stabiliser.

Preferably, the stabiliser is selected from the group consisting of diene-based compounds, phosphates, phenol compounds and epoxides, and mixtures thereof.

Conveniently, the composition of the invention may be combined with a flame retardant.

Advantageously, the flame retardant is selected from the group consisting of tri-(2- chloroethyl)-phosphate, (chloropropyl) phosphate, tri-(2,3-dibromopropyl)-phosphate, tri- (1 ,3-dichloropropyl)-phosphate, diammonium phosphate, various halogenated aromatic compounds, antimony oxide, aluminium trihydrate, polyvinyl chloride, a fluorinated iodocarbon, a fluorinated bromocarbon, trifluoro iodomethane, perfluoroalkyl amines, bromo-fluoroalkyl amines and mixtures thereof. Preferably, the heat transfer composition is a refrigerant composition.

In one embodiment, the invention provides a heat transfer device comprising a composition of the invention.

Preferably, the heat transfer device is a refrigeration device.

Conveniently, the heat transfer device is selected from the group consisting of automotive air conditioning systems, residential air conditioning systems, commercial air conditioning systems, residential refrigerator systems, residential freezer systems, commercial refrigerator systems, commercial freezer systems, chiller air conditioning systems, chiller refrigeration systems, and commercial or residential heat pump systems. Preferably, the heat transfer device is a refrigeration device or an air-conditioning system.

The compositions of the invention are particularly suitable for use in mobile air- conditioning applications, such as automotive air-conditioning systems (e.g. heat pump cycle for automotive air-conditioning).

Advantageously, the heat transfer device contains a centrifugal-type compressor.

The invention also provides the use of a composition of the invention in a heat transfer device as herein described.

According to a further aspect of the invention, there is provided a blowing agent comprising a composition of the invention.

According to another aspect of the invention, there is provided a foamable composition comprising one or more components capable of forming foam and a composition of the invention.

Preferably, the one or more components capable of forming foam are selected from polyurethanes, thermoplastic polymers and resins, such as polystyrene, and epoxy resins. According to a further aspect of the invention, there is provided a foam obtainable from the foamable composition of the invention.

Preferably the foam comprises a composition of the invention.

According to another aspect of the invention, there is provided a sprayable composition comprising a material to be sprayed and a propellant comprising a composition of the invention. According to a further aspect of the invention, there is provided a method for cooling an article which comprises condensing a composition of the invention and thereafter evaporating said composition in the vicinity of the article to be cooled.

According to another aspect of the invention, there is provided a method for heating an article which comprises condensing a composition of the invention in the vicinity of the article to be heated and thereafter evaporating said composition.

According to a further aspect of the invention, there is provided a method for extracting a substance from biomass comprising contacting the biomass with a solvent comprising a composition of the invention, and separating the substance from the solvent.

According to another aspect of the invention, there is provided a method of cleaning an article comprising contacting the article with a solvent comprising a composition of the invention.

According to a further aspect of the invention, there is provided a method for extracting a material from an aqueous solution comprising contacting the aqueous solution with a solvent comprising a composition of the invention, and separating the material from the solvent.

According to another aspect of the invention, there is provided a method for extracting a material from a particulate solid matrix comprising contacting the particulate solid matrix with a solvent comprising a composition of the invention, and separating the material from the solvent. According to a further aspect of the invention, there is provided a mechanical power generation device containing a composition of the invention.

Preferably, the mechanical power generation device is adapted to use a Rankine Cycle or modification thereof to generate work from heat.

According to another aspect of the invention, there is provided a method of retrofitting a heat transfer device comprising the step of removing an existing heat transfer fluid, and introducing a composition of the invention. Preferably, the heat transfer device is a refrigeration device or (a static) air conditioning system. Advantageously, the method further comprises the step of obtaining an allocation of greenhouse gas (e.g. carbon dioxide) emission credit.

In accordance with the retrofitting method described above, an existing heat transfer fluid can be fully removed from the heat transfer device before introducing a composition of the invention. An existing heat transfer fluid can also be partially removed from a heat transfer device, followed by introducing a composition of the invention.

In another embodiment wherein the existing heat transfer fluid is R-134a and the composition of the invention contains R-134a, R-1225ye, CO2 and optional components such as R-1234ze, a lubricant, a stabiliser and/or flame retardant can be added to the R- 134a in the heat transfer device, thereby forming the compositions of the invention, and the heat transfer device of the invention, in situ. Some of the existing R-134a may be removed from the heat transfer device prior to adding the R-1234ze(E) to facilitate providing the components of the compositions of the invention in the desired proportions.

Thus, the invention provides a method for preparing a composition and/or heat transfer device of the invention comprising introducing R-1225ye, CO2 and optional components such as R-1234ze(E), a lubricant, a stabiliser and/or flame retardant, into a heat transfer device containing an existing heat transfer fluid which is R-134a. Optionally, at least some of the R-134a is removed from the heat transfer device before introducing the R- 1234ze(E).

Of course, the compositions of the invention may also be prepared simply by mixing the R-1225ye, C0₂ (and optional components such as R-1234ze(E), R-134a, a lubricant, a stabiliser or an additional flame retardant) in the desired proportions. The compositions can then be added to a heat transfer device (or used in any other way as defined herein) that does not contain R-134a or any other existing heat transfer fluid, such as a device from which R-134a or any other existing heat transfer fluid have been removed. In a further aspect of the invention, there is provided a method for reducing the environmental impact arising from operation of a product comprising an existing compound or composition, the method comprising replacing at least partially the existing compound or composition with a composition of the invention. Preferably, this method comprises the step of obtaining an allocation of greenhouse gas emission credit.

By environmental impact we include the generation and emission of greenhouse warming gases through operation of the product.

As mentioned above, this environmental impact can be considered as including not only those emissions of compounds or compositions having a significant environmental impact from leakage or other losses, but also including the emission of carbon dioxide arising from the energy consumed by the device over its working life. Such environmental impact may be quantified by the measure known as Total Equivalent Warming Impact (TEWI). This measure has been used in quantification of the environmental impact of certain stationary refrigeration and air conditioning equipment, including for example supermarket refrigeration systems (see, for example, http://en.wikipedia.org/wiki/Total equivalent warming impact).

The environmental impact may further be considered as including the emissions of greenhouse gases arising from the synthesis and manufacture of the compounds or compositions. In this case the manufacturing emissions are added to the energy consumption and direct loss effects to yield the measure known as Life-Cycle Carbon Production (LCCP, see for example http://www.sae.org/events/aars/presentations/2007papasavva.pdf). The use of LCCP is common in assessing environmental impact of automotive air conditioning systems.

Emission credit(s) are awarded for reducing pollutant emissions that contribute to global warming and may, for example, be banked, traded or sold. They are conventionally expressed in the equivalent amount of carbon dioxide. Thus if the emission of 1 kg of R- 134a is avoided then an emission credit of 1x1300 = 1300 kg CO2 equivalent may be awarded. In another embodiment of the invention, there is provided a method for generating greenhouse gas emission credit(s) comprising (i) replacing an existing compound or composition with a composition of the invention, wherein the composition of the invention has a lower GWP than the existing compound or composition; and (ii) obtaining greenhouse gas emission credit for said replacing step.

In a preferred embodiment, the use of the composition of the invention results in the equipment having a lower Total Equivalent Warming Impact, and/or a lower Life-Cycle Carbon Production than that which would be attained by use of the existing compound or composition.

These methods may be carried out on any suitable product, for example in the fields of air-conditioning, refrigeration (e.g. low and medium temperature refrigeration), heat transfer, blowing agents, aerosols or sprayable propellants, gaseous dielectrics, cryosurgery, veterinary procedures, dental procedures, fire extinguishing, flame suppression, solvents (e.g. carriers for flavorings and fragrances), cleaners, air horns, pellet guns, topical anesthetics, and expansion applications. Preferably, the field is air- conditioning or refrigeration.

Examples of suitable products include heat transfer devices, blowing agents, foamable compositions, sprayable compositions, solvents and mechanical power generation devices. In a preferred embodiment, the product is a heat transfer device, such as a refrigeration device or an air-conditioning unit.

The existing compound or composition has an environmental impact as measured by GWP and/or TEWI and/or LCCP that is higher than the composition of the invention which replaces it. The existing compound or composition may comprise a fluorocarbon compound, such as a perfluoro-, hydrofluoro-, chlorofluoro- or hydrochlorofluoro-carbon compound or it may comprise a fluorinated olefin.

Preferably, the existing compound or composition is a heat transfer compound or composition such as a refrigerant. Examples of refrigerants that may be replaced include R-134a, R-152a, R-1234yf, R-410A, R-407A, R-407B, R-407C, R507, R-22 and R-404A. The compositions of the invention are particularly suited as replacements for R- 134a, R-152a or R-1234yf, especially R-134a or R-1234yf. Any amount of the existing compound or composition may be replaced so as to reduce the environmental impact. This may depend on the environmental impact of the existing compound or composition being replaced and the environmental impact of the replacement composition of the invention. Preferably, the existing compound or composition in the product is fully replaced by the composition of the invention.

The invention is illustrated by the following non-limiting examples. EXAMPLES

Modelled Performance Data

Generation of accurate physical property model

The physical properties of R-1225ye(Z) and R-1234ze(E) required to model refrigeration cycle performance, namely critical point, vapour pressure, liquid and vapour enthalpy, liquid and vapour density and heat capacities of vapour and liquid were accurately determined by experimental methods over the pressure range 0-200bar and temperature range -40 to 200°C, and the resulting data used to generate Helmholtz free energy equation of state models of the Span-Wagner type for the fluid in the NIST REFPROP Version 8.0 software, which is more fully described in the user guide www.nist.gov/srd/PDFfiles/REFPROP8.PDF. and is incorporated herein by reference. The variation of ideal gas enthalpy of these fluids with temperature was estimated using molecular modelling software Hyperchem v7.5 (which is incorporated herein by reference) and the resulting ideal gas enthalpy function was used in the regression of the equation of state for these fluids. The predictions of this model for R1234ze(E) were compared to the predictions yielded by use of the standard files for R-1234ze(E) included in REFPROP Version 9.0 (incorporated herein by reference). It was found that close agreement was obtained for each fluid's properties.

The vapour liquid equilibrium behaviour of R-1234ze(E) was studied in a series of binary pairs with carbon dioxide and R-134a over the temperature range -40 to +60°C, which encompasses the practical operating range of most refrigeration and air conditioning systems. The composition was varied over the full compositional space for each binary in the experimental programme, Mixture parameters for each binary pair were regressed to the experimentally obtained data and the parameters were also incorporated into the REFPROP software model.

The mixing parameters for R-1225ye(Z) with R-1234ze(E) and with carbon dioxide were selected as the default values generated by the REFPROP software.

The resulting software model was used to compare the performance of selected fluids of the invention with R-134a in an air conditioning cycle application.

Air conditioning cycle comparison

In a first comparison the behaviour of the fluids was assessed for a simple vapour compression cycle with conditions typical of automotive air conditioning duty in medium to high ambient temperatures. A reference fluid consisting of a ternary mixture of carbon dioxide, R-134a and R-1234ze(E) in the proportions 6%/9%/85% by weight was used in the comparison. In this comparison pressure drop effects were included in the model by assignation of a representative expected pressure drop to the reference fluid followed by estimation of the equivalent pressure drop for the mixed refrigerant of the invention in the same equipment at the same cooling capacity. The comparison was made on the basis of equal compressor displacement for the reference fluid and for the mixed fluids of the invention.

For the comparison the following assumptions were made for cycle conditions. Cycle conditions

The performance of the reference fluid was found to be as described in the table below. Results

COP 2.01

COP relative to Reference 100.0%

Achieved cooling capacity kW 8.50

Capacity relative to reference 100.0%

Suction pressure drop relative to reference 100.0%

Blend critical temperature °C 97.99

Blend critical pressure bar 39.73

Refrigeration effect kJ/kg 133.9

Pressure ratio 6.68

Mass flow through evaporator kg/hr 228.4

Compressor discharge temperature °C 106.9

Evaporator inlet pressure bar 3.77

Condenser inlet pressure bar 19.2

Evaporator inlet temperature °C 3.7

Evaporator dewpoint °C 6.3

Evaporator exit gas temperature °C 13.3

Evaporator glide (out-in) K 2.5

Compressor suction pressure bar 2.87

Compressor discharge pressure bar 19.2

Condenser dew point °C 68.8

Condenser bubble point X 51.2

Condenser exit liquid temperature X 46.2

Condenser glide (in-out) K 17.5

The generated performance data for selected compositions of the invention is set out in the following Tables. Discussion of results

It was found unexpectedly that in the addition of R-1225ye(Z) to binary mixtures of carbon dioxide and R-1234ze(E) where the carbon dioxide content was in the range 4- 12% w/w resulted in an increase in volumetric cooling capacity for the fluid until about 60% of the fluorocarbon content was R-1225ye(Z).

A similar effect was observed when R-1225ye(Z) was added to ternary mixtures of carbon dioxide, R-134a and R-1234ze(E). It was found also unexpectedly that when compositions of carbon dioxide and R- 1225ye(Z) with carbon dioxide were investigated that the energy efficiency (COP) of the fluid went through a maximum and that the performance was still elevated compared to that of pure R-1225ye(Z) while the carbon dioxide content was less than about 24% w/w. This is illustrated in the graph below.

Energy efficiency (COP) of R-7447R-1225ye(Z) mixtures

0% 5% 10% 15% 20% 25% 30%

R-744 content (% w/w)

In summary, the invention provides new compositions that exhibit a surprising combination of advantageous properties including good refrigeration performance, low flammability, low GWP, critical temperature and/or miscibility with lubricants compared to existing refrigerants such as R-134a and the proposed refrigerant R-1234yf.

The invention is defined by the claims.

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-80% R-1225ye(Z), 4-80% R 1234ze(E) 6% R-744, 10% R-134a

Composition C0₂/R-1225ye(Z), R- 6/56/ 6/60/ 6/64/ 6/68/ 6/72/ 6/76/ 6 134a/R-1234ze(E) % by weight► 10/28 10/24 10/20 10/16 10/12 10/8

COP 1.95 1.94 1.94 1.94 1.94 1.94 1.

COP relative to Reference 96.9% 96.8% 96.7% 96.6% 96.5% 96.5% 96. Achieved cooling capacity 8.52 8.50 8.47 8.45 8.42 8.39 8. Capacity relative to reference 100.3% 100.0% 99.8% 99.5% 99.1% 98.7% 98. Suction pressure drop relative to

reference 112.0% 112.3% 112.6% 112.7% 112.8% 112.7% 112.

Blend critical temperature 95.56 95.38 95.19 95.01 94.82 94.63 94. Blend critical pressure 39.61 39.48 39.33 39.16 38.97 38.76 38.

Refrigeration effect 119.6 118.9 118.3 117.7 117.1 116.6 11 Pressure ratio 6.64 6.65 6.66 6.68 6.70 6.71 6.

Mass flow through evaporator 256.3 257.2 257.9 258.5 258.8 259.0 25 Liquid injection mass flow 0.0 0.0 0.0 0.0 0.0 0.0 0. Compressor discharge temperature 103.8 103.7 103.5 103.4 103.3 103.1 10 Evaporator inlet pressure 4.02 4.02 4.01 4.01 4.00 3.99 3. Condenser inlet pressure 20.0 20.0 20.0 20.0 20.0 20.0 20. Evaporator inlet temperature 4.1 4.1 4.1 4.1 4.0 4.0 4. Evaporator dewpoint 5.9 5.9 5.9 5.9 6.0 6.0 6. Evaporator exit gas temperature 12.9 12.9 12.9 12.9 13.0 13.0 13. Evaporator glide (out-in) 1.8 1.8 1.9 1.9 1.9 2.0 2. Compressor suction pressure 3.01 3.01 3.00 2.99 2.99 2.97 2. Compressor discharge pressure 20.0 20.0 20.0 20.0 20.0 20.0 20. Condenser dew point 68.1 68.2 68.2 68.3 68.3 68.4 68. Condenser bubble point 51.9 51.8 51.8 51.7 51.7 51.6 51. Condenser exit liquid temperature 46.9 46.8 46.8 46.7 46.7 46.6 46. Condenser glide (in-out)

16.3 16.3 16.4 16.6 16.7 16.9 17.

5

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-76% R-1225ye(Z), 6-78% R- 1234ze(E), 8% R-744, 10% R-134a

Composition C0₂/R-1225ye(Z), R- 8/56/ 8/60/ 8/64/ 8/68/ 8/72/ 8/76/ 134a/R-1234ze(E) % by weight► 10/26 10/22 10/18 10/14 10/10 10/6

COP 1.95 1.95 1.95 1.95 1.94 1.94

COP relative to Reference 97.1% 97.0% 96.9% 96.8% 96.8% 96.8%

Achieved cooling capacity 9.39 9.37 9.35 9.32 9.29 9.26

Capacity relative to reference 110.5% 110.3% 110.0% 109.7% 109.4% 109.0%

Suction pressure drop relative to reference 119.4% 119.8% 120.0% 120.2% 120.3% 120.2%

Blend critical temperature 92.14 91.95 91.75 91.55 91.35 91.15 Blend critical pressure 40.27 40.13 39.97 39.80 39.61 39.39

Refrigeration effect 123.7 123.0 122.4 121.8 121.3 120.8 Pressure ratio 6.66 6.67 6.68 6.70 6.71 6.73

Mass flow through evaporator 273.2 274.2 275.0 275.6 276.0 276.1 Liquid injection mass flow 0.0 0.0 0.0 0.0 0.0 0.0 Compressor discharge temperature 106.7 106.6 106.4 106.3 106.2 106.1 Evaporator inlet pressure 4.37 4.37 4.37 4.36 4.36 4.35 Condenser inlet pressure 21.9 22.0 22.0 22.0 22.0 22.0 Evaporator inlet temperature 3.0 3.0 3.0 3.0 3.0 2.9 Evaporator dewpoint 7.0 7.0 7.0 7.0 7.0 7.1 Evaporator exit gas temperature 14.0 14.0 14.0 14.0 14.0 14.1 Evaporator glide (out-in) 3.9 3.9 4.0 4.0 4.1 4.2 Compressor suction pressure 3.30 3.29 3.29 3.28 3.27 3.26 Compressor discharge pressure 21.9 22.0 22.0 22.0 22.0 22.0 Condenser dew point 69.7 69.7 69.7 69.8 69.9 70.0 Condenser bubble point 50.3 50.3 50.3 50.2 50.1 50.0 Condenser exit liquid temperature 45.3 45.3 45.3 45.2 45.1 45.0 Condenser glide (in-out)

19.3 19.4 19.5 19.6 19.8 20.0

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-76% R-1225ye(Z), 4-76% R- 1234ze(E), 10% R-744, 10% R-134a

Composition C0₂/R-1225ye(Z), R- 10/56/ 10/60/ 10/64/ 10/68/ 10/72/ 10/76/ 134a/R-1234ze(E) % by weight► 10/24 10/20 10/16 10/12 10/8 10/4

COP 1.95 1.95 1.95 1.95 1.95 1.95

COP relative to Reference 97.2% 97.1% 97.0% 96.9% 96.9% 96.9%

Achieved cooling capacity 10.28 10.27 10.25 10.22 10.20 10.17

Capacity relative to reference 121.1% 120.9% 120.6% 120.3% 120.0% 119.7%

Suction pressure drop relative to reference 127.5% 127.9% 128.1% 128.3% 128.4% 128.4%

Blend critical temperature 88.92 88.72 88.51 88.30 88.09 87.88 Blend critical pressure 40.93 40.79 40.63 40.45 40.25 40.04

Refrigeration effect 127.2 126.5 125.9 125.4 124.9 124.4 Pressure ratio 6.64 6.65 6.67 6.68 6.70 6.72

Mass flow through evaporator 291.0 292.1 292.9 293.6 294.0 294.3 Liquid injection mass flow 0.0 0.0 0.0 0.0 0.0 0.0 Compressor discharge temperature 109.3 109.2 109.1 108.9 108.8 108.8 Evaporator inlet pressure 4.75 4.75 4.75 4.74 4.73 4.72 Condenser inlet pressure 23.9 23.9 24.0 24.0 24.0 24.0 Evaporator inlet temperature 2.1 2.0 2.0 2.0 1.9 1.9 Evaporator dewpoint 7.9 8.0 8.0 8.0 8.1 8.1 Evaporator exit gas temperature 14.9 15.0 15.0 15.0 15.1 15.1 Evaporator glide (out-in) 5.9 5.9 6.0 6.0 6.1 6.2 Compressor suction pressure 3.60 3.60 3.59 3.59 3.58 3.57 Compressor discharge pressure 23.9 23.9 24.0 24.0 24.0 24.0 Condenser dew point 70.8 70.9 70.9 71.0 71.1 71.2 Condenser bubble point 49.2 49.1 49.1 49.0 48.9 48.8 Condenser exit liquid temperature 44.2 44.1 44.1 44.0 43.9 43.8 Condenser glide (in-out)

21.7 21.8 21.9 22.0 22.2 22.4

Theoretical Performance Data of Selected R-744 /R1225ye(Z)/R-134a/R-1234ze(E) blends containing 4-72% R-1225ye(Z), 6-74% R- 1234ze(E), 12% R-744 and 10% R-134a

Composition C0₂//R-1225ye(Z)/R- 12/52/ 12/56/ 12/60/ 12/64/ 12/68/ 12/72/ 134a/R- 234ze(E) % by weight► 10/26 10/22 10/18 10/14 10/10 10/6

COP I.95 I.95 I.95 I.95 I.94 I.94

COP relative to Reference 97.1% 97.0% 96.9% 96.9% 96.8% 96.8%

Achieved cooling capacity II.22 II.21 II.19 II.17 II.15 II.12

Capacity relative to reference 132.1% 131.9% 131.7% 131.5% 131.2% 130.9%

Suction pressure drop relative to reference 135.5% 136.0% 136.4% 136.7% 136.9% 137.0%

Blend critical temperature 86.09 85.88 85.67 85.45 85.23 85.01 Blend critical pressure 41.73 41.60 41.46 41.29 41.11 40.91

Refrigeration effect 131.0 130.3 129.6 129.0 128.5 128.0 Pressure ratio 6.59 6.60 6.61 6.63 6.64 6.66

Mass flow through evaporator 308.3 309.6 310.7 311.6 312.3 312.9 Liquid injection mass flow 0.0 0.0 0.0 0.0 0.0 0.0 Compressor discharge temperature III.9 III.8 III.6 III.5 III.4 III.3 Evaporator inlet pressure 5.14 5.14 5.15 5.14 5.14 5.13 Condenser inlet pressure 25.8 25.9 25.9 25.9 26.0 26.0 Evaporator inlet temperature 1.1 1.1 1.1 1.1 1.0 1.0 Evaporator dewpoint 8.9 8.9 8.9 8.9 9.0 9.0 Evaporator exit gas temperature 15.9 15.9 15.9 15.9 16.0 16.0 Evaporator glide (out-in) 7.7 7.8 7.8 7.9 8.0 8.1 Compressor suction pressure 3.92 3.92 3.92 3.91 3.91 3.90 Compressor discharge pressure 25.8 25.9 25.9 25.9 26.0 26.0 Condenser dew point 71.7 71.7 71.8 71.9 71.9 72.0 Condenser bubble point 48.3 48.3 48.2 48.1 48.1 48.0 Condenser exit liquid temperature 43.3 43.3 43.2 43.1 43.1 43.0 Condenser glide (in-out)

23.4 23.5 23.6 23.7 23.9 24.1

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-80% R-1225ye(Z), 10-86% R- 1234ze(E), 6% R-744, 4% R-134a

5

Theoretical Performance Data of Selected R-744/R-1225ye/R-1 -1234ze(E) blends containing 4-80% R-1225ye(Z), 8-84% R- 1234ze(E), 8% R-744, 4% R-134a

Composition C0₂/R-1225ye(Z), R- 134a/R-1234ze(E) % by weight►

COP

COP relative to Reference

Achieved cooling capacity

Capacity relative to reference

Suction pressure drop relative to reference

Blend critical temperature

Blend critical pressure

Refrigeration effect

Pressure ratio

Mass flow through evaporator

Liquid injection mass flow

Compressor discharge temperature

Evaporator inlet pressure

Condenser inlet pressure

Evaporator inlet temperature

Evaporator dewpoint

Evaporator exit gas temperature

Evaporator glide (out-in)

Compressor suction pressure

Compressor discharge pressure

Condenser dew point

Condenser bubble point

Condenser exit liquid temperature

Condenser glide (in-out)

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-80% R-1225ye(Z), 6-82% R- 1234ze(E), 10% R-744, 4% R-134a

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-80% R-1225ye(Z), 4-80% R- 1234ze(E), 12% R-744, 4% R-134a

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-64% R-1225ye(Z), 32-92% R- 1234ze(E), 4% R-744, 0% R-134a

4/48/0/48 4/52/0/44 4/56/0/40 4/60/0/36 4/64/0/32

I.95 I .94 I .94 I .94 I .94 97.0% 96.8% 96.7% 96.5% 96.4%

7.41 7.40 7.39 7.37 7.35 87.2% 87.1% 86.9% 86.7% 86.5% 100.8% 101.3% 101.7% 102.1% 102.4%

100.39 100.23 100.07 99.90 99.74 38.33 38.25 38.15 38.03 37.90

115.7 114.9 114.1 113.4 112.7 6.60 6.61 6.61 6.62 6.63

230.6 231.8 233.0 234.0 234.8 0.0 0.0 0.0 0.0 0.0

100.0 99.8 99.6 99.4 99.2

3.54 3.54 3.55 3.55 3.55

17.4 17.4 17.4 17.4 17.4

5.2 5.2 5.2 5.2 5.2

4.8 4.8 4.8 4.8 4.8

I I.8 I I.8 I I .8 I I .8 I I .8 -0.4 -0.4 -0.4 -0.4 -0.5 2.63 2.63 2.63 2.63 2.63 17.4 17.4 17.4 17.4 17.4 66.4 66.4 66.4 66.4 66.4 53.6 53.6 53.6 53.6 53.6 48.6 48.6 48.6 48.6 48.6

12.7 12.7 12.7 12.8 12.8

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-64% R-1225ye(Z), 30-90% R- 1234ze(E), 6% R-744, 0% R-134a

Composition C0₂/R-1225ye(Z), R- 134a/R-1234ze(E) % by weight► 6/36/0/58 6/40/0/54 6/48/0/46 6/52/0/42 6/56/0/38 6/60/0/34 6/64/0/30

COP 1.97 1.97 1.96 1.95 1.95 1.95 1.95

COP relative to Reference 98.0% 97.8% 97.5% 97.3% 97.2% 97.0% 96.9%

Achieved cooling capacity 8.25 8.25 8.24 8.23 8.21 8.20 8.18

Capacity relative to reference 97.1% 97.1% 97.0% 96.8% 96.7% 96.5% 96.3%

Suction pressure drop relative to reference 105.2% 105.9% 107.3% 107.8% 108.3% 108.7% 109.1%

Blend critical temperature 97.23 97.06 96.72 96.54 96.36 96.18 96.00 Blend critical pressure 39.15 39.11 38.98 38.90 38.79 38.67 38.53

Refrigeration effect 123.3 122.4 120.6 119.7 119.0 118.2 117.5 Pressure ratio 6.67 6.67 6.67 6.68 6.68 6.69 6.70

Mass flow through evaporator 240.9 242.7 245.9 247.3 248.5 249.6 250.5 Liquid injection mass flow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compressor discharge temperature 103.9 103.6 103.2 103.0 102.8 102.6 102.5 Evaporator inlet pressure 3.82 3.84 3.86 3.87 3.87 3.87 3.87 Condenser inlet pressure 19.2 19.2 19.3 19.3 19.4 19.4 19.4 Evaporator inlet temperature 4.0 4.1 4.1 4.1 4.1 4.1 4.1 Evaporator dewpoint 6.0 5.9 5.9 5.9 5.9 5.9 5.9 Evaporator exit gas temperature 13.0 12.9 12.9 12.9 12.9 12.9 12.9 Evaporator glide (out-in) 1.9 1.9 1.8 1.8 1.8 1.8 1.8 Compressor suction pressure 2.88 2.88 2.89 2.89 2.90 2.89 2.89 Compressor discharge pressure 19.2 19.2 19.3 19.3 19.4 19.4 19.4 Condenser dew point 68.4 68.4 68.4 68.4 68.4 68.4 68.4 Condenser bubble point 51.6 51.6 51.6 51.6 51.6 51.6 51.6 Condenser exit liquid temperature 46.6 46.6 46.6 46.6 46.6 46.6 46.6 Condenser glide (in-out) 16.9 16.8 16.7 16.7 16.8 16.8 16.9

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-64% R-1225ye(Z), 28-88% R- 1234ze(E), 8% R-744, 0% R-134a

8/48/0/44 8/52/0/40 8/56/0/36 8/60/0/32 8/64/0/28

1.96 1.96 1.96 1.96 1.95 97.8% 97.6% 97.5% 97.4% 97.3%

9.10 9.09 9.07 9.06 9.04 107.1% 107.0% 106.8% 106.6% 106.4% 114.5% 115.1% 115.6% 116.1% 116.4%

93.26 93.07 92.88 92.69 92.49 39.65 39.56 39.45 39.32 39.17

124.8 123.9 123.2 122.4 121.8 6.69 6.70 6.70 6.71 6.72 262.4 263.9 265.2 266.4 267.3 0.0 0.0 0.0 0.0 0.0 106.1 105.9 105.7 105.5 105.4 4.20 4.21 4.22 4.22 4.22 21.2 21.3 21.3 21.3 21.3 3.0 3.0 3.0 3.0 3.0 7.0 7.0 7.0 7.0 7.0 14.0 14.0 14.0 14.0 14.0 3.9 3.9 3.9 3.9 4.0 3.17 3.18 3.18 3.18 3.17 21.2 21.3 21.3 21.3 21.3 70.0 70.0 70.0 70.0 70.0 50.0 50.0 50.0 50.0 50.0 45.0 45.0 45.0 45.0 45.0 19.9 19.9 19.9 20.0 20.1

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-64% R-1225ye(Z), 26-86% R- 1234ze(E), 10% R-744, 0% R-134a

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 4-64% R-1225ye(Z), 24-84% R- 1234ze(E), 12% R-744, 0% R-134a

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 72-96% R-1225ye(Z), 0% R- 1234ze(E), 4-28% R-744, 0% R-134a (with 100% 1225ye(Z) included for reference)

Composition C0₂/R-1225ye(Z), R-134a/R- 1234ze(E) % by weight► 16/84/0/0 18/82/0/0 20/80/0/0 22/78/0/0 24/76/0/0 26/74/0/0 28/72/0/0

COP 1.95 1.94 1.92 1.90 1.88 1.86 1.84

COP relative to Reference 96.9% 96.3% 95.6% 94.8% 93.8% 92.6% 91.4%

Achieved cooling capacity 12.65 13.63 14.60 15.57 16.52 17.45 18.36

Capacity relative to reference 148.9% 160.4% 171.9% 183.3% 194.5% 205.5% 216.2%

Suction pressure drop relative to reference 151.7% 161.4% 171.1% 181.0% 190.8% 200.7% 210.6%

Blend critical temperature 79.20 76.66 74.28 72.02 69.89 67.87 65.95

Blend critical pressure 40.79 41.60 42.42 43.24 44.06 44.89 45.71

Refrigeration effect 131.8 134.2 136.2 137.9 139.4 140.6 141.6

Pressure ratio 6.63 6.54 6.46 6.38 6.31 6.23 6.16

Mass flow through evaporator 345.6 365.8 386.0 406.4 426.6 446.8 466.9

Liquid injection mass flow 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Compressor discharge temperature 114.6 116.8 118.9 121.0 123.0 125.0 127.0

Evaporator inlet pressure 5.79 6.24 6.70 7.17 7.66 8.15 8.66

Condenser inlet pressure 29.3 31.3 33.3 35.4 37.5 39.6 41.7

Evaporator inlet temperature -1.1 -1.9 -2.6 -3.2 -3.7 -4.2 -4.5

Evaporator dewpoint 11.1 11.9 12.6 13.2 13.7 14.2 14.5

Evaporator exit gas temperature 18.1 18.9 19.6 20.2 20.7 21.2 21.5

Evaporator glide (out-in) 12.2 13.8 15.1 16.4 17.4 18.3 19.1

Compressor suction pressure 4.42 4.78 5.16 5.55 5.94 6.35 6.76

Compressor discharge pressure 29.3 31.3 33.3 35.4 37.5 39.6 41.7

Condenser dew point 74.1 74.4 74.5 74.6 74.5 74.3 74.1

Condenser bubble point 45.9 45.6 45.4 45.4 45.5 45.7 45.9

Condenser exit liquid temperature 40.9 40.6 40.4 40.4 40.5 40.7 40.9

Condenser glide (in-out) 28.2 28.8 29.1 29.2 29.0 28.7 28.1

5

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 80-92% R-1225ye(Z), 0% R- 1234ze(E), 4-16% R-744, 4% R-134a

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 74-86% R-1225ye(Z), 0% R- 1234ze(E), 4-16% R-744, 10% R-134a

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 78-88% R-1225ye(Z), 0% R- 1234ze(E), 4-14% R-744, 8% R-134a

Theoretical Performance Data of Selected R-744/R-1225ye/R-134a/R-1234ze(E) blends containing 78-90% R-1225ye(Z), 0% R- 1234ze(E), 4-16% R-744, 6% R-134a

Claims

1. A composition comprising 1 ,2,3,3,3-pentafluoropropene (R-1225ye), 1 ,1 ,1 ,2- tetrafluoroethane (R-134a) and from about 3 to about 25 % by weight carbon dioxide (C0₂, R-744).

2. A composition according to claim 1 comprising from about 3 to about 20 % by weight C0₂, for example from about 4 to about 18 % by weight C0₂.

3. A composition according to claim 2 comprising from about 4 to about 16 % by weight CO2.

4. A composition according to any of the preceding claims comprising at least about 50 % by weight R-1225ye, for example from about 60 to about 95 % by weight.

5. A composition according to claim 4 comprising from about 70 to about 92 % by weight R-1225ye.

6. A composition according to any of the preceding claims comprising up to about 40 % by weight R-134a, for example from about 2 to about 30 % by weight R-134a.

7. A composition according to claim 6 comprising from about 3 to about 20 % by weight R-134a, for example from about 4 to about 15 % by weight R-134a.

8. A composition comprising 1 ,2,3,3,3-pentafluoropropene (R-1225ye), carbon dioxide (C0₂, R-744), and 1 ,3,3,3-tetrafluoropropene (R-1234ze).

9. A composition according to claim 8 comprising up to about 30 % by weight CO2, for example from about 2 to about 25 % by weight C0₂.

10. A composition according to claim 8 or 9 comprising up to about 90 % by weight R-1225ye, for example from about 2 to about 85 % by weight.

11. A composition according to any of claims 8 to 10 comprising up to about 95 % by weight of R1234ze(E), for example from about 2 to about 92 % .

12. A composition according to any of claims 8 to 11 comprising from about 4 to about 80 % by weight R-1225ye, from about 2 to about 20 % by weight C0₂ and from about 10 to about 94 % by weight R-1234ze.

13. A composition according to any of claims 8 to 12 comprising from about 4 to about 70 % by weight R-1225ye, from about 2 to about 5 % by weight C0₂ and from about 20 to about 92 % by weight R-1234ze.

14. A composition according to any of claims 8 to 11 further comprising 1 ,1 ,1 ,2- tetrafluoroethane (R-134a), for example up to about 30 % by weight R-134a.

15. A composition according to claim 14 comprising from about 4 to about 85 % by weight R-1225ye, from about 2 to about 20 % by weight C0₂, from about 4 to about 85 % by weight of R-1234ze and from about 2 to about 20 % by weight R-134a.

16. A composition according to claim 15 comprising from about 5 to about 80 % by weight R-1225ye, from about 3 to about 15 % by weight CO2, from about 5 to about 80 % by weight of R-1234ze and from about 3 to about 15 % by weight R-134a.

17. A composition according to any of claims 8 to 16 wherein the R-1234ze is trans- 1 ,3,3,3-tetrafluoropropene (R-1234ze(E)).

18. A composition comprising from about 6 to about 28 % by weight carbon dioxide (C02, R-744) and from about 72 to about 94 % by weight 1 ,2,3,3,3-pentafluoropropene (R-1225ye).

19. A composition according to claim 18 comprising from about 6 to about 25 % by C0₂ and from about 75 to about 94 % by weight R-1225ye.

20. A composition according to claim 18 or 19 comprising from about 6 to about 20 % by weight C0₂ and from about 80 to about 94 % by weight R-1225ye.

21. A composition according to any of claims 18 to 20 comprising from about 6 to about 16 % by weight C0₂ and from about 84 to about 94 % by weight R-1225ye.

22. A composition according to any of claims 18 to 21 wherein the composition is substantially free of (i) any other hydrofluorocarbon compound, and/or (ii) any hydrocarbon.

23. A composition according to any of claims 18 to 22 consisting essentially of C0₂ and R-1225ye.

24. A composition according to any of the preceding claims wherein the R-1225ye is c s-1 ,2,3,3,3-pentafluoropropene (R-1225ye(Z)).

25. A composition according to any of the preceding claims, wherein the composition is less flammable than R-1234ze alone or R-1234yf alone.

26. A composition according to claim 25 wherein the composition has:

(a) a higher flammable limit;

(b) a higher ignition energy; and/or

(c) a lower flame velocity

compared to R-1234ze alone or R-1234yf alone.

27. A composition according to any of the preceding claims which is non-flammable.

28. A composition according to any of the preceding claims which has a critical temperature of greater than about 65 °C, preferably greater than about 70 °C.

29. A composition comprising a lubricant and a composition according to any of the preceding claims.

30. A composition according to claim 29, wherein the lubricant is selected from mineral oil, silicone oil, polyalkyi benzenes (PABs), polyol esters (POEs), polyalkylene glycols (PAGs), polyalkylene glycol esters (PAG esters), polyvinyl ethers (PVEs), poly (alpha-olefins) and combinations thereof, preferably wherein the lubricant is selected from PAGs or POEs.

31. A composition comprising a stabiliser and a composition according to any of the preceding claims.

32. A composition according to claim 31 , wherein the stabiliser is selected from diene-based compounds, phosphates, phenol compounds and epoxides, and mixtures thereof.

33. A composition comprising a flame retardant and a composition according to any of the preceding claims.

34. A composition according to claim 33, wherein the flame retardant is selected from the group consisting of tri-(2-chloroethyl)-phosphate, (chloropropyl) phosphate, tri- (2,3-dibromopropyl)-phosphate, tri-(1 ,3-dichloropropyl)-phosphate, diammonium phosphate, various halogenated aromatic compounds, antimony oxide, aluminium trihydrate, polyvinyl chloride, a fluorinated iodocarbon, a fluorinated bromocarbon, trifluoro iodomethane, perfluoroalkyi amines, bromo-fluoroalkyl amines and mixtures thereof.

35. A composition according to any of the preceding claims which is a refrigerant composition.

36. A heat transfer device containing a composition as defined in any one of claims 1 to 35.

37. Use of a composition defined in any of claims 1 to 35 in a heat transfer device.

38. A heat transfer device according to claim 36 or a use according to claim 37 wherein the heat transfer device is a refrigeration device.

39. A heat transfer device or use according to claims 36 to 38 wherein the heat transfer device is selected from group consisting of automotive air conditioning systems, residential air conditioning systems, commercial air conditioning systems, residential refrigerator systems, residential freezer systems, commercial refrigerator systems, commercial freezer systems, chiller air conditioning systems, chiller refrigeration systems, and commercial or residential heat pump systems, preferably wherein the heat transfer device is an automobile air-conditioning system.

40. A heat transfer device or use according to claims 36 to 39 wherein the heat transfer device contains a compressor.

41. A blowing agent comprising a composition as defined in any of claims 1 to 35.

42. A foamable composition comprising one or more components capable of forming foam and a composition as defined in any of claims 1 to 35, wherein the one or more components capable of forming foam are selected from polyurethanes, thermoplastic polymers and resins, such as polystyrene, and epoxy resins, and mixtures thereof.

43. A foam obtainable from the foamable composition as defined in claim 42.

44. A foam comprising a composition as defined in any of claims 1 to 35.

45. A sprayable composition comprising material to be sprayed and a propellant comprising a composition as defined in any of claims 1 to 35.

46. A method for cooling an article which comprises condensing a composition defined in any of claims 1 to 35 and thereafter evaporating the composition in the vicinity of the article to be cooled.

47. A method for heating an article which comprises condensing a composition as defined in any one of claims 1 to 35 in the vicinity of the article to be heated and thereafter evaporating the composition.

48. A method for extracting a substance from biomass comprising contacting biomass with a solvent comprising a composition as defined in any of claims 1 to 35, and separating the substance from the solvent.

49. A method of cleaning an article comprising contacting the article with a solvent comprising a composition as defined in any of claims 1 to 35.

50. A method of extracting a material from an aqueous solution or from a particulate solid matrix comprising contacting the aqueous solution or the particulate solid matrix with a solvent comprising a composition as defined in any of claims 1 to 35, and separating the material from the solvent.

51. A mechanical power generation device containing a composition as defined in any of claims 1 to 35.

52. A mechanical power generating device according to claim 51 which is adapted to use a Rankine Cycle or modification thereof to generate work from heat.

53. A method of retrofitting a heat transfer device comprising the step of removing an existing heat transfer composition, and introducing a composition as defined in any one of claims 1 to 35.

54. A method of claim 53 wherein the heat transfer device is a refrigeration device.

55. A method according to claim 54 wherein the heat transfer device is an air conditioning system, preferably an automobile air conditioning system.

56. A method for reducing the environmental impact arising from the operation of a product comprising an existing compound or composition, the method comprising replacing at least partially the existing compound or composition with a composition as defined in any one of claims 1 to 35.

57. A method for preparing a composition as defined in any of claims 1 to 35, and/or a heat transfer device as defined in any of claims 36 or 38 to 40, which composition or heat transfer device contains R-134a, the method comprising introducing R-1225ye, CO2 and optionally R-1234ze, a lubricant, a stabiliser and/or a flame retardant, into a heat transfer device containing an existing heat transfer fluid which is R-134a.

58. A method according to claim 57 comprising the step of removing at least some of the existing R-134a from the heat transfer device before introducing the R-1225ye, CO2 and optionally R-1234ze(E), the lubricant, the stabiliser and/or the flame retardant.

59. A method for generating greenhouse gas emission credit comprising (i) replacing an existing compound or composition with a composition as defined in any one of claims 1 to 35, wherein the composition as defined in any one of claims 1 to 35 has a lower GWP than the existing compound or composition; and (ii) obtaining greenhouse gas emission credit for said replacing step.

60. A method of claim 59 wherein the use of the composition of the invention results in a lower Total Equivalent Warming Impact, and/or a lower Life-Cycle Carbon Production than is attained by use of the existing compound or composition.

61. A method of claim 59 or 60 carried out on a product from the fields of air- conditioning, refrigeration, heat transfer, blowing agents, aerosols or sprayable propellants, gaseous dielectrics, cryosurgery, veterinary procedures, dental procedures, fire extinguishing, flame suppression, solvents, cleaners, air horns, pellet guns, topical anesthetics, and expansion applications.

62. A method according to claim 56 or 61 wherein the product is selected from a heat transfer device, a blowing agent, a foamable composition, a sprayable composition, a solvent or a mechanical power generation device, preferably a heat transfer device.

63. A method according to claim 62 wherein the product is a heat transfer device.

64. A method according to any of claims 56 to 63 wherein the existing compound or composition is a heat transfer composition, preferably wherein the heat transfer composition is a refrigerant selected from R-134a, R-1234yf, R-152a, R-404A, R-410A, R-507, R-407A, R-407B, R-407D, R-407E and R-407F.

65. Any novel heat transfer composition substantially as hereinbefore described, optionally with reference to the examples.