Refrigerant composition (M20)

Abstract

The present invention relates to a refrigerant composition, the refrigerant composition comprising: 76-86 mol% propylene; and 12-24 mol% propane. The present invention further relates to a method for the preparation of the refrigerant composition and the use of the refrigerant composition in a vapour-compression refrigeration system.

Description

Refrigerant Composition (M20)TECHNICAL FIELD

[0001] The present invention relates to a refrigerant composition. More specifically, the refrigerant composition of the present invention is a blend of hydrocarbons.BACKGROUND ART

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

[0003] Hydrofluorocarbon (HFC) refrigerants were commercialized in the 1990s as replacements for the ozone depleting chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants. While HFC refrigerants do not damage the ozone, they are still considered to have a high global warming potential (GWP). The GWP of a refrigerant is a measure of its global warming impact relative to the impact of the same quantity of carbon dioxide over a 100 year period. HFCs generally have a greater ability to trap heat in the atmosphere compared to a similar mass of carbon dioxide. A further issue with high GWP HFC refrigerants is their relatively poor energy efficiency. The use of such refrigerants therefore increases energy consumption. High GWP HFC refrigerants dominate the market worldwide, leading to them being seen as a rapidly growing source of energy consumption and greenhouse gas emissions, both direct and indirect. The disadvantages associated with high GWP HFC refrigerants have resulted in individual countries introducing plans to phase out the use of high GWP HFC refrigerants by placing restrictions or tariffs on their import.

[0004] Alternative refrigerant compositions having a low GWP are required to replace HFC refrigerants. Alternative refrigerants must meet a strict set of criteria in order to be considered a viable option. For example, such refrigerants must demonstrate suitable performance, efficiency, safety, stability and material compatibility with all components in the refrigeration system. It is also important that the refrigerant has a sufficiently short atmospheric lifetime. Hydrocarbon-based refrigerants have been developed as an alternative to HFC refrigerants. These refrigerants typically consist of a singlehydrocarbon substance. The overall energy efficiency of these refrigerants is therefore limited by the thermodynamic properties of that particular hydrocarbon. While hydrocarbon blends have been considered, the particular hydrocarbons used and the relative concentrations of each hydrocarbon change the thermodynamic properties of the refrigerant blend. For example, the pressure temperature relationship, the pressure enthalpy relationship and / or the temperature glide of the refrigerant will change depending on the hydrocarbon type and their relative concentrations. These changes are also influenced by intermolecular forces in the blend, making the impact of the blend composition on the thermodynamic properties of the refrigerant difficult to predict. This makes it challenging to design a refrigerant blend having thermodynamic properties that match those of a particular HFC refrigerant that is to be replaced across all operating conditions.

[0005] Throughout this specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0006] The invention described herein may include one or more range of values (e.g. mol%, etc). A range of values will be understood to include all values within the range, including the values defining the range, and values adjacent to the range which lead to the same or substantially the same outcome as the values immediately adjacent to that value which define the boundary to the range.SUMMARY OF INVENTION

[0007] In accordance with a first aspect of the present invention, there is provided a refrigerant composition, the refrigerant composition comprising:76-86 mol% propylene; and12-24 mol% propane.

[0008] Throughout this specification, unless the context requires otherwise, the term "refrigerant composition" or variations such as "refrigerant(s)", will be understood torefer to a fluid that is used for heat transfer purposes in vapour-compression refrigeration systems, such as, for example, refrigeration and air conditioning systems.

[0009] In one form of the present invention, the refrigerant composition is suitable for use as a refrigerant in a vapour-compression refrigeration system. Preferably, the refrigerant composition is suitable for use as a refrigerant in a vapour-compression refrigeration system compatible with refrigerant R-32.

[0010] Preferably, the refrigerant composition does not contain any components that are not suitable for use in a vapour-compression refrigeration system.

[0011] In one form of the present invention, the refrigerant composition comprises less than 0.1 mol% 2 methyl propane.

[0012] In an alternative form of the present invention, the refrigerant composition further comprises:0.1 -4 mol% 2 methyl propane.

[0013] Preferably, the refrigerant composition of the present invention comprises less than 10 ppm water.

[0014] Preferably, the refrigerant composition of the present invention has a purity of >99.5%.

[0015] In accordance with a further embodiment of the present invention, there is provided a method for preparing a refrigerant composition, the method comprising blending 76-86 mol% propylene and 12-24 mol% propane. Preferably, the method comprises blending 76-86 mol% propylene, 12-24 mol% propane and 0.1 -4 mol% 2 methyl propane.

[0016] In accordance with a further embodiment of the present invention, there is provided a vapour-compression refrigeration system comprising a refrigerant composition comprising 76-86 mol% propylene and 12-24 mol% propane. Preferably, the refrigerant comprises 76-86 mol% propylene, 12-24 mol% propane and 0.1 -4 mol% 2 methyl propane.

[0017] In accordance with a further embodiment of the present invention, there is provided a method for operating a vapour-compression refrigeration system, the method comprising: charging the vapour-compression refrigeration system with a refrigerant composition comprising 76-86 mol% propylene and 12-24 mol% propane; and operating the vapour-compression refrigeration system.

[0018] Preferably, the refrigerant composition comprises 76-86 mol% propylene, 12-24 mol% propane and 0.1-4 mol% 2 methyl propane.

[0019] Preferably, the vapour-compression refrigeration system is compatible with refrigerant R-32.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:Figures 1 to 3 depict graphs showing the comparison of the thermodynamic properties of three refrigerant compositions of the present invention compared to a commercially available HFC refrigerant.DESCRIPTION OF EMBODIMENTS

[0021] The present invention relates to a refrigerant composition. The present invention comprises a blend of three different hydrocarbons at specific relative concentrations, namely:76-86 mol% propylene; and12-24 mol% propane.

[0022] In a preferred embodiment, the refrigerant composition comprises:76-86 mol% propylene;12-24 mol% propane; and0.1 -4 mol% 2-methyl propane.

[0023] The refrigerant composition of the present invention is intended to provide a low GWP alternative to existing HFC refrigerants. In particular, the refrigerant composition of the present invention is tailored to replace HFC refrigerant R-32. The inventors have found that the refrigerant composition may be directly added to systems designed for R- 32, without the need for any other mechanical modifications.

[0024] Throughout the specification, the unit “mol%” should be understood to refer to the concentration of a component in the composition expressed as the number of moles of that component relative to the total number of moles in the mixture, expressed as a percentage.

[0025] Propylene, also referred to as propene, is a gaseous hydrocarbon having the chemical formula CH3CH=CH2. In one embodiment, the refrigerant composition comprises 77-85 mol% propylene. In one embodiment, the refrigerant composition comprises 78-84 mol% propylene.

[0026] In one embodiment, the refrigerant composition comprises 78-84 mol% propylene. In one embodiment, the refrigerant composition comprises 78-83 mol% propylene. In one embodiment, the refrigerant composition comprises 78-82 mol% propylene. In one embodiment, the refrigerant composition comprises 78-81 mol% propylene. In one embodiment, the refrigerant composition comprises 78-80 mol% propylene.

[0027] In one embodiment, the refrigerant composition comprises 79-84 mol% propylene. In one embodiment, the refrigerant composition comprises 79-83 mol% propylene. In one embodiment, the refrigerant composition comprises 79-82 mol% propylene In one embodiment, the refrigerant composition comprises 79-81 mol% propylene.

[0028] In one embodiment, the refrigerant composition comprises 80-84 mol% propylene. In one embodiment, the refrigerant composition comprises 80-83 mol% propylene. In one embodiment, the refrigerant composition comprises 80-82 mol% propylene.

[0029] In one embodiment, the refrigerant composition comprises 81 -84 mol% propylene. In one embodiment, the refrigerant composition comprises 81 -83 mol% propylene.

[0030] In one embodiment, the refrigerant composition comprises 82-84 mol% propylene.

[0031] In one embodiment, the refrigerant composition comprises about 76 mol% propylene. In one embodiment, the refrigerant composition comprises about 77 mol% propylene. In one embodiment, the refrigerant composition comprises about 78 mol% propylene. In one embodiment, the refrigerant composition comprises about 79 mol% propylene. In one embodiment, the refrigerant composition comprises about 80 mol% propylene. In one embodiment, the refrigerant composition comprises about 81 mol% propylene. In one embodiment, the refrigerant composition comprises about 82 mol% propylene. In one embodiment, the refrigerant composition comprises about 83 mol% propylene. In one embodiment, the refrigerant composition comprises about 84 mol% propylene. In one embodiment, the refrigerant composition comprises about 85 mol% propylene. In one embodiment, the refrigerant composition comprises about 86 mol% propylene.

[0032] A suitable source of propylene is refrigerant R-1270. Refrigerant R-1270 is a commercially available refrigerant having greater than 99.5% propylene. R-1270 may be used as the propylene component of the refrigerant composition of the present invention. For example, the refrigerant composition of the present invention may comprise 76-86 mol% R-1270.

[0033] Propane is a gaseous hydrocarbon having the chemical formula CH3CH2CH3. In one embodiment, the refrigerant composition comprises 13-23 mol% propane. In one embodiment, the refrigerant composition comprises 13-22 mol% propane.

[0034] In one embodiment, the refrigerant composition comprises 13-21 mol% propane.In one embodiment, the refrigerant composition comprises 13-20 mol% propane. In one embodiment, the refrigerant composition comprises 13-19 mol% propane. In one embodiment, the refrigerant composition comprises 13-18 mol% propane. In one embodiment, the refrigerant composition comprises 13-17 mol% propane. In one embodiment, the refrigerant composition comprises 13-16 mol% propane. In one embodiment, the refrigerant composition comprises 13-15 mol% propane. In one embodiment, the refrigerant composition comprises 13-14 mol% propane.

[0035] In one embodiment, the refrigerant composition comprises 14-22 mol% propaneIn one embodiment, the refrigerant composition comprises 14-21 mol% propane. In one embodiment, the refrigerant composition comprises 14-20 mol% propane. In one embodiment, the refrigerant composition comprises 14-19 mol% propane. In one embodiment, the refrigerant composition comprises 14-18 mol% propane. In one embodiment, the refrigerant composition comprises 14-17 mol% propane. In one embodiment, the refrigerant composition comprises 14-16 mol% propane. In one embodiment, the refrigerant composition comprises 14-15 mol% propane.

[0036] In one embodiment, the refrigerant composition comprises 15-22 mol% propane.In one embodiment, the refrigerant composition comprises 15-21 mol% propane. In one embodiment, the refrigerant composition comprises 15-20 mol% propane. In one embodiment, the refrigerant composition comprises 15-19 mol% propane. In one embodiment, the refrigerant composition comprises 15-18 mol% propane. In one embodiment, the refrigerant composition comprises 15-17 mol% propane. In one embodiment, the refrigerant composition comprises 15-16 mol% propane.

[0037] In one embodiment, the refrigerant composition comprises 16-22 mol% propane. In one embodiment, the refrigerant composition comprises 16-21 mol% propane. In one embodiment, the refrigerant composition comprises 16-20 mol% propane. In one embodiment, the refrigerant composition comprises 16-19 mol% propane. In one embodiment, the refrigerant composition comprises 16-18 mol% propane. In one embodiment, the refrigerant composition comprises 16-17 mol% propane.

[0038] In one embodiment, the refrigerant composition comprises 17-22 mol% propane. In one embodiment, the refrigerant composition comprises 17-21 mol% propane. In oneembodiment, the refrigerant composition comprises 17-20 mol% propane. In one embodiment, the refrigerant composition comprises 17-19 mol% propane. In one embodiment, the refrigerant composition comprises 17-18 mol% propane.

[0039] In one embodiment, the refrigerant composition comprises 18-22 mol% propane. In one embodiment, the refrigerant composition comprises 18-21 mol% propane. In one embodiment, the refrigerant composition comprises 18-20 mol% propane. In one embodiment, the refrigerant composition comprises 18-19 mol% propane.

[0040] In one embodiment, the refrigerant composition comprises 19-22 mol% propane. In one embodiment, the refrigerant composition comprises 19-21 mol% propane. In one embodiment, the refrigerant composition comprises 19-20 mol% propane.

[0041] In one embodiment, the refrigerant composition comprises 20-22 mol% propane. In one embodiment, the refrigerant composition comprises 20-21 mol% propane.

[0042] In one embodiment, the refrigerant composition comprises 21 -22 mol% propane.

[0043] In one embodiment, the refrigerant composition comprises about 12 mol% propane. In one embodiment, the refrigerant composition comprises about 13 mol% propane. In one embodiment, the refrigerant composition comprises about 14 mol% propane. In one embodiment, the refrigerant composition comprises about 15 mol% propane. In one embodiment, the refrigerant composition comprises about 16 mol% propane. In one embodiment, the refrigerant composition comprises about 17 mol% propane. In one embodiment, the refrigerant composition comprises about 18 mol% propane. In one embodiment, the refrigerant composition comprises about 19 mol% propane. In one embodiment, the refrigerant composition comprises about 20 mol% propane. In one embodiment, the refrigerant composition comprises about 21 mol% propane. In one embodiment, the refrigerant composition comprises about 22 mol% propane. In one embodiment, the refrigerant composition comprises about 23 mol% propane. In one embodiment, the refrigerant composition comprises about 24 mol% propane.

[0044] A suitable source of propane is refrigerant R-290. Refrigerant R-290 is a commercially available refrigerant having greater than 99.5% propane. R-290 may be used as the propane component of the refrigerant composition of the present invention.For example, the refrigerant composition of the present invention may comprise 12-24 mol% R-290.

[0045] In one embodiment, the refrigerant composition comprises 76-86 mol% propylene and 14-24 mol% propane. In one embodiment, the refrigerant composition comprises 76-85 mol% propylene and 14-24 mol% propane. In one embodiment, the refrigerant composition comprises 80-86 mol% propylene and 14-20 mol% propane. In one embodiment, the refrigerant composition comprises 79-86 mol% propylene and 14- 20 mol% propane. In one embodiment, the refrigerant composition comprises 81 -86 mol% propylene and 14-18 mol% propane. In one embodiment, the refrigerant composition comprises 82-86 mol% propylene and 14-18 mol% propane. In one embodiment, the refrigerant composition comprises 79-86 mol% propylene and 12-19 mol% propane. In one embodiment, the refrigerant composition comprises 81 -86 mol% propylene and 12-19 mol% propane. In one embodiment, the refrigerant composition comprises 77-85 mol% propylene and 13-23 mol% propane. In one embodiment, the refrigerant composition comprises 78-84 mol% propylene and 13-22 mol% propane.

[0046] 2-methyl propane, also known as isobutane, i-butane or methylpropane, is a gaseous hydrocarbon having the chemical formula HC(CH3)3. In one embodiment, the refrigerant composition comprises less than 0.1 mol% 2-methyl propane.

[0047] In one embodiment, the refrigerant composition comprises 0.1 -4 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 0.1 -3 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 0.1 -2 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 0.1 -1 mol% 2-methyl propane.

[0048] In one embodiment, the refrigerant composition comprises 0.5-4 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 0.5-3.5 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 0.5-3 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 0.5-2.5 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 0.5- 2 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 0.5-1.5 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 0.5-1 mol% 2-methyl propane.

[0049] In one embodiment, the refrigerant composition comprises 1 -4 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 1 -3.5 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 1 -3 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 1 -2.5 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 1 -2 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 1 -1.5 mol% 2-methyl propane.

[0050] In one embodiment, the refrigerant composition comprises 1.5-4 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 1.5-3.5 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 1.5-3 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 1.5-2.5 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 1 .5- 2 mol% 2-methyl propane.

[0051] In one embodiment, the refrigerant composition comprises 2-4 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 2-3.5 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 2-3 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 2-2.5 mol% 2-methyl propane.

[0052] In one embodiment, the refrigerant composition comprises 2.5-4 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 2.5-3.5 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises 2.5-3 mol% 2-methyl propane.

[0053] In one embodiment, the refrigerant composition comprises 3-4 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises 3-3.5 mol% 2- methyl propane.

[0054] In one embodiment, the refrigerant composition comprises 3.5-4 mol% 2-methyl propane.

[0055] In one embodiment, the refrigerant composition comprises about 0.5 mol% 2- methyl propane. In one embodiment, the refrigerant composition comprises about 1 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprisesabout 1.5 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises about 2 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises about 2.5 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises about 3 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises about 3.5 mol% 2-methyl propane. In one embodiment, the refrigerant composition comprises about 4 mol% 2-methyl propane.

[0056] A suitable source of 2-methyl propane is refrigerant R-600a. Refrigerant R-600a is a commercially available refrigerant having greater than 99.5% 2-methyl propane. R- 600a may be used as the 2-methyl propane component of the refrigerant composition of the present invention. For example, the refrigerant composition of the present invention may comprise 0.1 -4 mol% R-600a.

[0057] In one embodiment, the refrigerant composition of the present invention comprises 77-85 mol% propylene; 13-23 mol% propane; and 0.5-4 mol% 2-methyl propane.

[0058] In one embodiment, the refrigerant composition of the present invention comprises 78-84 mol% propylene; 13-22 mol% propane; and 0.5-3 mol% 2-methyl propane.

[0059] In one embodiment, the refrigerant composition of the present invention comprises: 79-86 mol% propylene; 12-19 mol% propane; and 1 -2 mol% 2-methyl propane. In one embodiment, the refrigerant composition of the present invention comprises: 80-85 mol% propylene; 13-18 mol% propane; and 1 -2 mol% 2-methyl propane. In one embodiment, the refrigerant composition of the present invention comprises: 81 -84 mol% propylene; 14-17 mol% propane; and 1 -2 mol% 2-methyl propane.

[0060] In a preferred form of the present invention, the refrigerant composition comprises less than 10 ppm water.

[0061] In a preferred form of the present invention, the refrigerant composition a purity of >99.5%.

[0062] In one embodiment, the refrigerant composition contains less than 1 mol% impurities. In one embodiment, the refrigerant composition contains less than 0.5mol% impurities. In this context, impurities should be understood to be any substance other than propylene, propane and 2 methyl propane.

[0063] In one embodiment, the refrigerant composition contains less than 1 mol% of any hydrocarbon other than propylene, propane and 2 methyl propane. In one embodiment, the refrigerant composition contains less than 0.5 mol% of any hydrocarbon other than propylene, propane and 2 methyl propane.

[0064] The refrigerant composition of the present invention is prepared by blending the hydrocarbon components together. Any suitable means of blending hydrocarbons known in the art may be used to prepare the refrigerant composition of the present invention. For example, the hydrocarbon components may be added separately to an appropriate compressed gas cylinder, often referred to as a service cylinder. The total capacity of the compressed gas cylinder is used to calculate the weight of each respective hydrocarbon component in the refrigerant composition. The weight of the cylinder is measured to ensure the correct amount of each hydrocarbon is added.

[0065] As the main components of the refrigerant composition of the present invention are hydrocarbons, the refrigerant composition has a low GWP.

[0066] The inventors of the present invention have found that when applied correctly to refrigeration and air conditioning equipment, the refrigerant composition of the present invention demonstrates improved energy savings over existing commercial refrigerants. Without wishing to be bound by theory, it is understood that the refrigerant composition of the present invention can operate at comparatively lower operating pressures which results in reduced energy consumption. Lower operating pressure also reduces wear on the compressor and fittings. Furthermore, the inventors have found that by blending multiple hydrocarbons in the ratios of the present invention, the pressure temperature relationship of the resulting refrigerant composition will follow a similar curve to that of conventional HFC refrigerants, such as R-32, across a wider temperature range than single-component hydrocarbon refrigerants. This allows the refrigerant composition of the present inventions to be used in refrigeration equipment designed for conventional HFC refrigerants without the need for mechanical modifications or operational limitations.Examples

[0067] A series of tests were conducted to compare the thermodynamic properties of a refrigerant blend of the present invention against commercially available R-32 refrigerant. Three refrigerant compositions were prepared by blending various quantities of commercially available R-1270, R-290 and R-600a. The three refrigerant compositions were prepared according to Table 1 :Table 1 : Refrigerant Compositions

[0068] The performance tests were conducted on a commercially available wall mounted reverse cycle split system air conditioner as per AS / NZS 3823.1 .1 :2012.

[0069] The results of the performance tests for Refrigerants A to C are shown in Figures 1 to 3 respectively.

[0070] Each of the refrigerant compositions of the present invention demonstrated a substantial reduction in operating pressures compared to R32. The lower operating pressure will reduce the work required by the compressor, resulting in a reduction in electricity consumption and wear on the compressor. These lower operating discharge pressures will also reduce the pressure exerted on pipe work, joints, hoses, fittings and the like, reducing the likelihood of leaks. This is expected to extend the working life of the refrigeration equipment. The results also show that the pressure I temperature relationship of the refrigerant composition of the present invention follows a similar curve as the conventional refrigerant, albeit at lower pressures. The inventors understand that this will assist in the use of the refrigerant composition in refrigerant equipment designed for conventional refrigerants.

[0071] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. The invention includes all such variation and modifications. The invention also includes all of the steps, features, formulations and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features.

Claims

CLAIMS1 . A refrigerant composition, the refrigerant composition comprising:76-86 mol% propylene; and12-24 mol% propane.

2. A refrigerant composition according to claim 1 , further comprising:0.1 -4 mol% 2 methyl propane.

3. A refrigerant composition according to claim 1 or 2, wherein the refrigerant composition is suitable for use as a refrigerant in a vapour-compression refrigeration system.

4. A refrigerant composition according to claim 3, wherein the vapour-compression refrigeration system is compatible with refrigerant R-32.

5. A refrigerant composition according to any of the preceding claims, wherein the refrigerant composition comprises 77-85 mol% propylene.

6. A refrigerant composition according to any of the preceding claims, wherein the refrigerant composition comprises 78-84 mol% propylene.

7. A refrigerant composition according to any of claims 1 to 4, wherein the refrigerant composition comprises 79-86 mol% propylene.

8. A refrigerant composition according to any of the preceding claims, wherein the refrigerant composition comprises 12-19 mol% propane.

9. A refrigerant composition according to any of the preceding claims, wherein the refrigerant composition comprises 13-18 mol% propane10. A refrigerant composition according to any of claims 2 to 9, wherein the refrigerant composition comprises 1 -2 mol% 2-methyl propane.

11. A refrigerant composition according to any of the preceding claims, wherein the combined amount of propylene, propane and 2 methyl propane is greater than 99.0 mol%.

12. A refrigerant composition according to any of the preceding claims, wherein the refrigerant composition comprises less than 10 ppm water.

13. A method for preparing a refrigerant composition, the method comprising blending 76-86 mol% propylene, 12-24 mol% propane and 0.1 -4 mol% 2 methyl propane.

14. A vapour-compression refrigeration system comprising the refrigerant of any of claims 1 -12.

15. A method for operating a vapour-compression refrigeration system, the method comprising: charging the vapour-compression refrigeration system with the refrigerant of any of claims 1 -12; and operating the vapour-compression refrigeration system.

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