Composition

Abstract

The present invention provides an alternative refrigerant that has improved properties, such as a low GWP, and yet has acceptable cooling performance, flammability, and toxicity characteristics, and can be used in existing equipment, such as chillers, with little or no modification. [Solution] A composition comprising: (i) 1,1-difluoroethene (vinylidene fluoride, R-1132a); (ii) carbon dioxide (CO2, R-744); (iii) pentafluoroethane (R-125); and (iv) one or more of trifluoromethane (R-23) and hexafluoroethane (R-116).

Description

[Technical field]

[0001] The present invention relates to compositions, preferably heat transfer compositions, especially ultra-low temperature heat transfer compositions that may be suitable as replacements for existing refrigerants such as R-23, R-13B1, R-508A or R-508B. [Background technology]

[0002] The listing or discussion of a prior-published document or any background art in this specification should not necessarily be construed as an acknowledgement that the document or background art is part of the state of the art or is common general knowledge.

[0003] Mechanical cooling systems and associated heat transfer devices are well known, e.g. heat pumps and air conditioning systems. In such systems, a refrigerant liquid evaporates at low pressure and removes heat from the surrounding zone. The produced vapour is then compressed and sent to a condenser where it condenses and releases heat to a second zone. The condensed liquid is returned to the evaporator via an expansion valve, thus completing the cycle. The mechanical energy required to compress the vapour and pump the liquid is provided, for example, by an electric motor or an internal combustion engine.

[0004] "Blast freezers" are devices used to quickly freeze food or medicines by contacting the product to be frozen within a sealed compartment with recirculating cold air.

[0005] Conventional food flash freezing utilizes a single-stage cooling system to rapidly cool food to a temperature of about -18 to about -30° C. A typical refrigerant used for this would be R-404A (44% by weight pentafluoroethane (R-125), 52% by weight 1,1,1-trifluoroethane (R-143a) and 4% by weight 1,1,1,2-tetrafluoroethane (R-134a)).

[0006] It has been found that the use of lower refrigeration temperatures allows for ocean transport of high-value seafood (e.g., sea urchins, swordfish, tuna) over long distances. Some shipping companies offer refrigerated shipping container systems ("reefers") that can maintain temperatures of approximately -60°C. In these cascade systems, a low-temperature cooling loop using trifluoromethane (R-23) cools the container air to -60°C and dumps its heat into a second high-temperature cooling loop (using R-134a or R-404A). The high-temperature stage dumps heat into the surrounding air. Although these systems work well, the GWP of R-23 is very high at 14,800. It would therefore be desirable to use a less flammable or non-flammable fluid with a lower GWP that could replace R-23 in this application.

[0007] The pharmaceutical industry also uses rapid freezing at low temperatures to freeze and preserve active ingredients and other biologically derived materials, as described in the reference monograph "Freeze-Drying / Lyophilization of Pharmaceutical and Biological Products, Third Edition," edited by Louis Rey and published by CRC Press on April 19, 2016, which is incorporated herein by reference. Specific examples include, but are not limited to, insulin, vaccines, and tissue samples. Traditional refrigerants used in these systems include bromotrifluoromethane (R-13B1), R-23, R-508A (39% R-23, 61% R-116) and R-508B (46% R-23, 56% R-116), with operating temperatures ranging from about -60°C to about -90°C.

[0008] There are several refrigerant and application characteristics that must be considered when developing a viable replacement for R-23 (and other low-temperature refrigerants used in cascade systems): ·Low flammability Suitable operating temperature Similar operating pressure to R-23 Refrigerant performance (e.g. cooling capacity, energy efficiency) Minimum temperature gradient of the coolant ·Low Global Warming Potential (GWP)

[0009] Therefore, the design of a suitable refrigerant involves making several informed choices of composition and components to arrive at a viable alternative.

[0010] One method to assess non-flammability is to apply the flammability analysis methodology defined in ASHRAE Standard 34:2016, which specifies a range of leak scenarios that should be applied to refrigerant mixtures to identify the worst-case potentially flammable compositions.

[0011] If the fluid is to be used as a retrofit or conversion fluid for existing equipment, or as a "drop-in" for new equipment (e.g., using an essentially unchanged R-23 system design), non-flammability is highly desirable since the existing design will have been based on the use of a non-flammable fluid. Particularly in large systems and marine (reefer) applications, non-flammability under all circumstances (including leakage) is highly desirable.

[0012] It is also advantageous for the fluid to have acceptably low toxicity properties.

[0013] Volumetric capacity (a measure of the cooling power achievable in a compressor of a given size) and energy efficiency are important considerations for any composition with heat transfer properties. This is especially true in cascade operation, since any inefficiency in the low temperature stage will increase the power consumption of the top compressor of the cascade.

[0014] R-170 (ethane) has a very low GWP, acceptable cooling performance, and low toxicity, but its high flammability limits its applications. For example, safety regulations may limit the maximum charge of refrigerant in equipment.

[0015] Although R-744 (carbon dioxide) is non-flammable, it cannot be used alone in the lower stages of a low-temperature cascade system because its operating temperature is below the triple point of R-744, -56.7°C. This means that solid carbon dioxide (dry ice) can form in the low-pressure sections of the system, causing blockages, poor control, and inefficient operation.

[0016] R-1132a (1,1-difluoroethene, also known as vinylidene fluoride) also has a low GWP and acceptable toxicity. The flammability of R-1132a is low compared to ethane, but it is still in ASHRAE flammability class 2 ("low flammability"). The thermodynamic energy efficiency of pure R-1132a is close to that of R-508 and better than that of R-23, but its cooling capacity is low compared to R-508 and R-23. DISCLOSURE OF THEINVENTION

[0017] Thus, there is a need to provide alternative refrigerants that have improved properties, such as a lower GWP, yet still have acceptable cooling performance, flammability and toxicity characteristics, and that can be used in existing equipment, such as chillers, with little or no modification.

[0018] The present invention addresses these and other deficiencies by providing a composition comprising 1,1-difluoroethene (vinylidene fluoride, R-1132a), carbon dioxide (CO2, R-744), pentafluoroethane (R-125), and one or more of trifluoromethane (R-23) and hexafluoroethane (R-116).

[0019] The present invention also provides the use of the composition of the present invention as a refrigerant, preferably a low temperature refrigerant suitable for use in a deep freezing device. The temperature reached by using the composition of the present invention as a refrigerant may be below -60°C, for example below -70°C, preferably below -80°C, or even below -90°C.

[0020] Surprisingly, it has been found that the compositions of the present invention exhibit a combination of suitable combustion characteristics, operating pressures similar to R-23, cooling performance equal to or better than R-23, desirable temperature gradients and low GWP.

[0021] The composition of the present invention may contain about 1 to about 90% by weight of R-1132a, for example about 1 to about 80% by weight, about 1 to about 70% by weight, or about 1 to about 60% by weight. Preferably, the composition may contain about 1 to about 50% by weight of R-1132a, for example about 5 to about 45% by weight, about 10 to about 45% by weight, about 15 to about 40% by weight. Advantageously, the composition may contain about 20 to about 40% by weight of R-1132a, preferably about 25 to about 35% by weight of R-1132a.

[0022] The composition of the present invention may contain about 1 to about 90% by weight, for example, about 1 to about 80% by weight, about 5 to about 70% by weight, or about 10 to about 60% by weight of carbon dioxide. Preferably, the composition may contain about 25 to about 60% by weight, for example, about 30 to about 55% by weight, and even more preferably about 35 to about 50% by weight of carbon dioxide.

[0023] The compositions of the present invention are surprisingly capable of operating below −56.7° C. (the triple point of carbon dioxide) without the formation of dry ice within the system.

[0024] The composition of the present invention may contain about 1 to about 90% by weight, for example, about 1 to about 80% by weight, about 1 to about 70% by weight, or about 1 to about 60% by weight of R-125. Preferably, the composition contains about 1 to about 50% by weight, for example, about 5 to about 45% by weight, about 5 to about 30% by weight, or even about 10 to about 25% by weight.

[0025] The composition of the present invention may contain about 1 to about 90% by weight, for example, about 1 to about 80% by weight, about 1 to about 70% by weight, or about 1 to about 60% by weight of the fourth component. Preferably, the composition of the present invention may contain about 1 to about 50% by weight of the fourth component.

[0026] In one embodiment, the fourth component comprises or is R-23. Thus, a preferred composition of the present invention comprises R-1132a, CO2, R-125 and R-23.

[0027] In a preferred embodiment, a composition is provided that includes about 20 to about 40% by weight of R-1132a, about 30 to about 60% by weight of carbon dioxide, about 1 to about 20% by weight of R-23, and about 1 to about 35% by weight of R-125.

[0028] Advantageously, a composition is provided comprising about 25 to about 35% by weight of R-1132a, about 35 to about 50% by weight of carbon dioxide, about 5 to about 15% by weight of R-23, and about 5 to about 30% by weight of R-125.

[0029] In a preferred embodiment, a composition is provided that includes about 25 to about 30% by weight of R-1132a, about 35 to about 50% by weight of carbon dioxide, about 10 to about 25% by weight of R-125, and about 5 to about 20% by weight of R-23.

[0030] In another embodiment, the fourth component comprises or is R-116. Thus, a preferred composition of the present invention comprises R-1132a, CO2, R-125 and R-116.

[0031] In a preferred embodiment, a composition is provided that includes about 30 to about 60% by weight carbon dioxide, about 10 to about 40% by weight R-1132a, about 5 to about 30% by weight R-125, and about 1 to about 20% by weight R-116.

[0032] A preferred composition of the present invention comprises from about 35 to about 55 weight percent carbon dioxide, from about 15 to about 35 weight percent R-1132a, from about 10 to about 30 weight percent R-125, and from about 1 to about 15 weight percent R-116.

[0033] Advantageously, a composition is provided comprising about 25 to about 35% by weight (e.g., about 30%) R-1132a, about 40 to about 50% by weight (e.g., about 45%) carbon dioxide, about 15 to about 25% by weight (e.g., about 20%) R-125, and about 1 to about 15% by weight (e.g., about 5%) R-116.

[0034] Preferably, R-1132a is present in an amount less than 50 mole %. The ASHRAE fractionation analysis described above requires evaluation of the liquid and vapor composition during vapor leakage from the cylinder and should be performed at two levels of refrigerant charge (15% and 90% of maximum charge) and at temperatures ranging from -40° C. to +60° C. Compositions containing less than 50 mole %, preferably less than 30 mole %, of R-1132a will be mildly flammable, or preferably non-flammable, according to the fractionation analysis.

[0035] ASHRAE fractionation analysis is conservative in nature. Like R-23, the mixtures of this invention typically have a critical temperature close to ambient temperature. This means that if the system is not operating and is allowed to warm to ambient temperature, the mixture may be above its critical temperature. In this case, it exists as a homogeneous supercritical fluid. Thus, any leakage would be of the bulk composition, not of fractionated vapor. Thus, if the bulk fluid is non-flammable, the composition may be used in a variety of applications without significant risk of creating a flammable atmosphere.

[0036] In one embodiment, the composition may consist essentially of the above components.

[0037] The term "consisting essentially of" means that the composition of the present invention is substantially free of other components, in particular additional (hydro)(fluoro) compounds (e.g., (hydro)(fluoro)alkanes or (hydro)(fluoro)alkenes) known for use in heat transfer compositions. The term "consisting of" is included within the meaning of "consisting essentially of".

[0038] In one embodiment, the compositions of the present invention are substantially free of any components (other than those specified) that have heat transfer properties. For example, the compositions of the present invention may be substantially free of any other hydrofluorocarbon compounds.

[0039] By "substantially free" and "substantially free" we include the meaning that the compositions of the present invention contain no more than 0.5% by weight, preferably no more than 0.1% by weight, of the above listed components based on the total weight of the composition.

[0040] The compositions of the present invention may be azeotropic or near-azeotropic, preferably azeotropic.

[0041] By azeotropic compositions we mean compositions that have the same composition in both phases in vapor-liquid equilibrium and whose boiling point is lower than that of the pure component. All azeotropic compositions of the present invention have been found to exhibit a positive deviation from ideality. By pseudoazeotropic compositions we mean liquid compositions that have a vapor pressure higher than that of the lower boiling pure component when measured at a comparable temperature, but whose equilibrium vapor composition may differ from the liquid composition.

[0042] All of the chemicals described herein are commercially available, for example, the fluorochemicals are available from Apollo Scientific (UK) and carbon dioxide is available from liquefied gas suppliers such as Linde AG.

[0043] As used herein, all percentage amounts referred to for compositions herein, including the claims, are by weight based on the total weight of the composition, unless otherwise specified.

[0044] The term "about" when used in connection with numerical values ​​of component amounts in weight percent includes the meaning of ±0.5 weight percent, such as ±0.2 weight percent or ±0.1 weight percent.

[0045] For the avoidance of doubt, it is understood that the upper and lower limits set forth in the ranges of amounts of components in the compositions of the invention described herein can be interchanged in any way so long as the resulting range is within the broadest scope of the invention.

[0046] The compositions of the present invention have an ozone depletion potential of zero.

[0047] It is desirable to have a GWP as low as possible while respecting other constraints regarding flammability, performance and operating temperature range.

[0048] The composition has a GWP of less than 7,400, for example less than 5,000, less than 4,000, or preferably less than 3,700. The composition advantageously has a GWP of less than 3,000, less than 2,500, less than 2,000, less than 1,500, or even less than 1,000.

[0049] Generally, the compositions of the present invention have reduced flammability hazards when compared to R-1132a.

[0050] Flammability may be determined in accordance with ASHRAE Standard 34:2016, which incorporates ASTM Standard E-681 using the test methodology per Addendum 34, dated 2004, the entire contents of which are incorporated herein by reference.

[0051] In some embodiments, the composition has one or more of (a) a higher lower flammability limit, (b) a higher ignition energy (sometimes referred to as spontaneous ignition energy or pyrolysis), or (c) a lower flame speed compared to R-1132a alone. Preferably, the composition of the present invention is less flammable compared to R-1132a in one or more of the lower flammability limit at 23°C, the lower flammability limit at 60°C, the width of the flammable range at 23°C or 60°C, the spontaneous ignition temperature (pyrolysis temperature), the minimum ignition energy in dry air, or the flame speed. The flammability limit is determined according to the method specified in ASHRAE Standard34:2016, and the spontaneous ignition temperature is determined in a 500 ml glass flask by the method of ASTM E659-78.

[0052] In a preferred embodiment, the compositions of the present invention are non-flammable. For example, the compositions of the present invention are non-flammable at a test temperature of 60° C. using ASHRAE methodology. Advantageously, mixtures of vapors in equilibrium with the compositions of the present invention are also non-flammable at any temperature between about −40° C. and 60° C.

[0053] In some applications, it may not be necessary to classify a formulation as non-flammable per ASHRAE methodology; for example, if it is physically impossible to leak a cooling system charge into the environment and create a flammable mixture, it is possible to develop a fluid whose flammability limits in air are low enough to make it safe for use in that application.

[0054] In one embodiment, the compositions of the present invention have a flammability that can be classified as 1 or 2L according to the ASHRAE classification system, indicating non-flammable (Class 1) or slightly flammable fluids with flame speeds of less than 10 cm / s (Class 2L).

[0055] Temperature gradients can be managed within the system and gradients below approximately 10 K are tolerable with only a minor effect on performance. Gradients above approximately 10 K may cause expected degradation in performance unless the heat exchanger is designed to accommodate gradient effects.

[0056] The compositions of the present invention preferably have a temperature gradient in the evaporator or condenser of less than about 10 K, even more preferably less than about 7 K, such as less than about 5 K (e.g., less than 3 K). "Temperature gradient" is the term given to the temperature change that occurs during the evaporation or condensation of a non-azeotropic refrigerant mixture.

[0057] The critical temperature of the heat transfer composition must be higher than the maximum expected condenser temperature. This is because cycle efficiency usually decreases as the critical temperature is approached. When this occurs, the latent heat of the refrigerant decreases, so more heat release occurs in the condenser by cooling the gaseous refrigerant, which requires more area per unit of heat transferred. The critical temperature of R-508B is about 11°C, and that of R-23 is about 26°C.

[0058] In one embodiment, the compositions of the present invention have a critical temperature greater than about 0°C, preferably greater than about 10°C, and more preferably greater than about 25°C.

[0059] The compositions of the present invention typically have a volumetric cooling capacity that is at least 85% of the volumetric cooling capacity of R-23 under equivalent cycle conditions. Preferably, the compositions of the present invention have a volumetric cooling capacity that is at least 90% of the volumetric cooling capacity of R-23, such as from about 95% to about 120% (e.g., from about 96% to about 115%) of the volumetric cooling capacity of R-23.

[0060] When used as a refrigerant, the compositions of the present invention are typically capable of reaching temperatures below -60°C, preferably below -70°C, for example below -80°C, whilst maintaining an evaporation pressure above atmospheric pressure.

[0061] In one embodiment, the cycle efficiency (coefficient of performance, COP) of the compositions of the present invention is at least 95% and / or within about 5% of the incumbent refrigerant fluid (e.g., R-23) that it replaces.

[0062] Advantageously, the compressor discharge temperature of the compositions of the present invention is within about 15K, preferably within about 10K, or even within about 5K of the existing refrigerant fluid which it replaces.

[0063] The compositions of the present invention are generally suitable for use in existing designs of equipment, such as cryogenic cooling equipment, and are compatible with all types of lubricants currently used with established HFC refrigerants. They may optionally be stabilized or compatibilized with mineral oils by the use of appropriate additives.

[0064] Preferably, the compositions of the present invention, when used in heat transfer devices, are combined with a lubricant.

[0065] Advantageously, the lubricant is selected from the group consisting of mineral oil, silicone oil, polyalkylbenzene (PAB), polyol ester (POE), polyalkylene glycol (PAG), polyalkylene glycol ester (PAG ester), polyvinyl ether (PVE), poly(alpha-olefin), and combinations thereof. PAG and POE, especially the latter, are currently the preferred lubricants for the compositions of the present invention.

[0066] Advantageously, the lubricant further comprises a stabilizer. The lubricant may preferably further comprise pentane (e.g., n-pentane or isopentane). The pentane may be present in an amount of about 1 to about 10% by weight, such as about 2 to about 6% by weight, of the refrigerant charge (e.g., a composition comprising pentane, lubricant and heat transfer composition).

[0067] Preferably, the stabilizer is selected from the group consisting of diene-based compounds, phosphates, phenolic compounds and epoxides, and mixtures thereof.

[0068] Advantageously, the compositions of the present invention may be combined with a flame retardant.

[0069] 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, aluminum trihydrate, polyvinyl chloride, fluorinated iodocarbons, fluorinated bromocarbons, trifluoroiodomethane, perfluoroalkylamines, bromofluoroalkylamines and mixtures thereof.

[0070] In one embodiment, the present invention provides a heat transfer device comprising the composition of the present invention.

[0071] Preferably, the heat transfer device is a cooling device.

[0072] Conveniently, the heat transfer device is a cryogenic cooling system, such as a blast freezer.

[0073] Advantageously, the heat transfer device comprises a cascade system.

[0074] The present invention also provides the use of the compositions of the present invention in the heat transfer devices described herein.

[0075] According to a further aspect of the invention, there is provided a method of cooling an article, comprising condensing a composition of the invention and then evaporating the composition in the vicinity of the article to be cooled.

[0076] According to another aspect of the invention, there is provided a method of heating an article, the method comprising condensing a composition of the invention in the vicinity of the article to be heated and thereafter evaporating the composition.

[0077] According to a further aspect of the invention there is provided a method of extracting a material from a biomass comprising contacting the biomass with a solvent comprising the composition of the invention and separating the material from the solvent.

[0078] According to another aspect of the invention, there is provided a method of cleaning an article, comprising contacting the article with a solvent comprising the composition of the invention.

[0079] According to a further aspect of the invention, there is provided a method of extracting a material from an aqueous solution comprising contacting the aqueous solution with a solvent comprising the composition of the invention and separating the material from the solvent.

[0080] According to another aspect of the invention, there is provided a method of 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.

[0081] According to another aspect of the present invention, there is provided a method of retrofitting a heat transfer device, comprising the steps of removing an existing heat transfer fluid and introducing a composition of the present invention. Preferably, the heat transfer device is a refrigeration device, more preferably the device is an ultra-low temperature refrigeration system such as a blast freezer. Preferably, the refrigeration system cools the compartment to less than about -55°C, preferably less than about -60°C, more preferably less than about -85°C or even less than -90°C.

[0082] Advantageously, the method further comprises the step of obtaining an allocation of greenhouse gas (eg carbon dioxide) emission rights.

[0083] According to the above retrofit method, the existing heat transfer fluid can be completely removed from the heat transfer device before introducing the composition of the present invention. The existing heat transfer fluid can also be partially removed from the heat transfer device before introducing the composition of the present invention.

[0084] The compositions of the present invention may also be prepared by simply mixing R-1132a, carbon dioxide, R-125 and the fourth component (and any further components such as lubricants, stabilizers or additional flame retardants) in the desired proportions. The composition can then be added to a heat transfer device (or used in any other manner as defined herein).

[0085] In a further aspect of the invention there is provided a method of reducing the environmental impact resulting from the operation of a product comprising an existing compound or composition, the method comprising at least partially replacing the existing compound or composition with a composition of the invention, preferably comprising the step of obtaining greenhouse gas emission allowances.

[0086] Environmental impacts include the generation and emission of greenhouse gases due to the operation of the product.

[0087] As mentioned above, this environmental impact can be considered to include not only emissions of compounds or compositions that have significant environmental impact due to leakage or other losses, but also emissions of carbon dioxide resulting from the energy consumed by the equipment during operation. Such environmental impacts may be quantified by an index known as the Total Equivalent Warming Impact (TEWI). This index has been used to quantify the environmental impact of certain fixed cooling and air conditioning equipment, such as, for example, supermarket cooling systems (see, for example, http: / / en.wikipedia.org / wiki / Total_equivalent_warming_impact).

[0088] The environmental impact may further be considered to include greenhouse gas emissions resulting from the synthesis and manufacture of the compound or composition. In this case, the manufacturing emissions are added to the energy consumption and direct loss effects to obtain a metric known as the Life Cycle Carbon Footprint (LCCP, see for example http: / / www.sae.org / events / aars / presentations / 2007papasavva.pdf). The use of LCCP is common in assessing the environmental impact of automotive air conditioning systems.

[0089] Emission allowances are awarded for reducing emissions of pollutants that contribute to global warming and may, for example, be banked, traded or sold. They are usually expressed in terms of carbon dioxide equivalents. Thus, if 1 kg of R-23 emissions is avoided, an emission allowance is awarded for 1 x 14,800 = 14,800 kg of CO2 equivalent.

[0090] In another embodiment of the present invention, there is provided a method of generating greenhouse gas emission credits, the method comprising: (i) replacing an existing compound or composition with a composition of the present invention, where the composition of the present invention has a lower GWP than the existing compound or composition; and (ii) acquiring greenhouse gas emission credits for the replacement step.

[0091] In a preferred embodiment, use of the compositions of the present invention results in devices having a lower total equivalent warming impact and / or a lower life cycle carbon footprint than is achieved by use of existing compounds or compositions.

[0092] These methods may be implemented for any suitable product in the fields of, for example, air conditioning, refrigeration (e.g., low and medium temperature refrigeration), heat transfer, gas dielectrics, flame suppression, solvents (e.g., carriers for flavors and fragrances), cleaning agents, topical anesthetics, and expansion applications. Preferably, the field is cryogenic refrigeration.

[0093] Examples of suitable articles include heat transfer devices, solvents, and mechanical power generating devices. In a preferred embodiment, the article is a heat transfer device, such as a refrigeration device or a cryogenic cooling system.

[0094] The existing compound or composition has a higher environmental impact as measured by GWP and / or TEWI and / or LCCP than the composition of the present invention that it replaces. The existing compound or composition may include fluorocarbon compounds, such as perfluorocarbon compounds, hydrofluorocarbon compounds, chlorofluorocarbon compounds, or hydrochlorofluorocarbon compounds, or may include fluorinated olefins.

[0095] Preferably, the existing compound or composition is a heat transfer compound or composition, such as a refrigerant. Examples of refrigerants that can be replaced include ULT refrigerants, such as R-508A, R-508B, R-23, and R-13B1.

[0096] To reduce the environmental impact, any amount of existing compounds or compositions may be replaced. This may depend on the environmental impact of the existing compounds or compositions to be replaced and the environmental impact of the replacement composition of the present invention. Preferably, the existing compounds or compositions in the product are completely replaced by the composition of the present invention.

[0097] The invention is illustrated by the following non-limiting examples. EXAMPLES

[0098] Compositions of R-1132a, R-744, R-125 and R-23 The performance of the quaternary compositions of the present invention was modeled and the results are shown in the following table, which gives the GWP, condenser and evaporator gradients, capacity and COP for R-23, discharge temperature differential and condenser pressure differential, with the contents shown as weight percent unless otherwise specified.

[0099] The cycle conditions used in the modeling are shown in Table 1. [Table 1]

[0100] The thermodynamic models used for mixture calculations use a cubic equation of state to model the gas phase and a Gibbs free energy correlation (Wilson equation) to model the liquid phase and temperature correlation of component vapor pressures. Binary interaction parameters for the fluids were correlated with measured phase equilibrium data when available.

[0101] A number of compositions have been identified that have volumetric capacities significantly higher than that of R-23 and may be better suited for new system designs that take advantage of the fluid properties. [Table 2A] [Table 2B]

[0102] Compositions of R-1132a, R-744, R-125, and R-116 The performance of the quaternary compositions of the present invention was modeled and the results are shown in the following table, which lists the GWP, condenser and evaporator gradients, capacity and COP relative to R-23, discharge temperature and condenser pressure differentials, maximum VDF of vapor and liquid, and mole percent of R-1132a. The table lists contents as weight percent unless otherwise specified.

[0103] The conditions used are as described in Table 1. [Table 3A] [Table 3B]

[0104] In summary, the compositions of the present invention exhibit an unexpected and advantageous combination of properties, including: (i) low or non-flammability; (ii) low GWP compared to existing ultra-low temperature refrigerants (e.g., R-23); and (iii) equivalent or improved cooling performance, e.g., in terms of low gradients and / or cooling capacity and / or energy efficiency, at relevant operating temperatures and pressures compared to existing ultra-low temperature refrigerants (e.g., R-23).

[0105] The preferences and options of a given aspect, feature, or parameter of the invention should be considered as disclosed in combination with any and all preferences and options with respect to all other aspects, features, and parameters of the invention, unless the context dictates otherwise.

[0106] The present invention encompasses the following aspects. [Aspect 1] 1. A composition comprising: (i) 1,1-difluoroethene (vinylidene fluoride, R-1132a), (ii) Carbon dioxide (CO2, R-744); (iii) pentafluoroethane (R-125), (iv) one or more of trifluoromethane (R-23) and hexafluoroethane (R-116). [Aspect 2] 2. The composition of embodiment 1, comprising about 1 to about 90 weight % of R-1132a. [Aspect 3] The composition of embodiment 2, comprising about 1 to about 50 weight % R-1132a. [Aspect 4] 4. The composition of any one of aspects 1 to 3, comprising about 1 to about 90% by weight of carbon dioxide. [Aspect 5] 5. The composition of embodiment 4, comprising about 5 to about 70% by weight of carbon dioxide. [Aspect 6] 6. The composition of any one of aspects 1-5, comprising about 1 to about 90 wt. % R-125. [Aspect 7] 7. The composition of embodiment 6, comprising about 1 to about 50 wt. % R-125. [Aspect 8] The composition of any one of aspects 1 to 7, comprising about 1 to about 90 wt % of the fourth component. [Aspect 9] The composition of embodiment 8, comprising about 1 to about 50 weight % of a fourth component (iv). [Aspect 10] 10. The composition of any one of aspects 1-9, comprising about 20 to about 40% by weight of R-1132a, about 30 to about 60% by weight of carbon dioxide, about 1 to about 20% by weight of R-23, and about 1 to about 35% by weight of R-125. [Aspect 11] 11. The composition of embodiment 10, comprising: about 25 to about 35% by weight of R-1132a; about 35 to about 50% by weight of carbon dioxide; about 5 to about 15% by weight of R-23; and about 5 to about 30% by weight of R-125. [Aspect 12] 10. The composition of any one of aspects 1-9, comprising about 25 to about 30% by weight of R-1132a, about 35 to about 50% by weight of carbon dioxide, about 10 to about 25% by weight of R-125, and about 5 to about 20% by weight of R-23. [Aspect 13] 10. The composition of any one of aspects 1-9, comprising about 30 to about 60% by weight carbon dioxide, about 10 to about 40% by weight R-1132a, about 5 to about 30% by weight R-125, and about 1 to about 20% by weight R-116. [Aspect 14] 14. The composition of any one of the preceding aspects, wherein the R-1132a is present in an amount less than 50 mol %. [Aspect 15] The composition of embodiment 14, wherein R-1132a is present in an amount less than 30 mol %. [Aspect 16] 16. The composition of any one of aspects 1-15, consisting essentially of the above components. [Aspect 17] Aspect 17. The composition of any one of aspects 1-16, which is azeotropic or pseudo-azeotropic. [Aspect 18] 18. The composition of any one of aspects 1-17, wherein the composition is less flammable than R-1132a alone. [Aspect 19] The composition has the following properties compared to R-1132a alone: a. Higher flammability limits; b. Higher ignition energy, and / or c. Lower flame speed 20. The composition of embodiment 18, having the following structure: [Aspect 20] 20. The composition of any one of the preceding aspects, wherein the composition is non-flammable. [Aspect 21] 21. The composition according to any one of the preceding aspects, wherein the temperature gradient in the evaporator or condenser is less than about 10 K, preferably less than about 7 K. [Aspect 22] 22. The composition of any one of the preceding aspects, wherein the critical temperature is greater than about 0° C., preferably greater than about 10° C. [Aspect 23] 23. The composition of any one of the preceding aspects, having a volumetric cooling capacity that is at least 90%, preferably at least 95%, of the volumetric cooling capacity of R-23 under equivalent cycle conditions. [Aspect 24] 24. The composition of any one of aspects 1-23, having a cycle efficiency (coefficient of performance, COP) that is at least 95% and / or within about 5% of the incumbent refrigerant fluid it replaces. [Aspect 25] 25. The composition of any one of the preceding aspects, having a compressor discharge temperature within 15 K of the compressor discharge temperature of R-23 at equivalent cycle conditions. [Aspect 26] A composition comprising a lubricant and the composition of any one of embodiments 1 to 25. [Aspect 27] 27. The composition of claim 26, wherein the lubricant is selected from mineral oil, silicone oil, polyalkylbenzene (PAB), polyol ester (POE), polyalkylene glycol (PAG), polyalkylene glycol ester (PAG ester), polyvinyl ether (PVE), poly(alpha-olefin), and combinations thereof, preferably the lubricant is selected from PAG or POE. [Aspect 28] 28. The composition of embodiment 27, wherein the composition further comprises pentane. [Aspect 29] A composition comprising a stabilizer and the composition of any one of embodiments 1 to 28. [Aspect 30] 30. The composition of embodiment 29, wherein the stabilizer is selected from diene compounds, phosphates, phenolic compounds, and epoxides, and mixtures thereof. [Aspect 31] A composition comprising a flame retardant and the composition of any one of aspects 1 to 30. [Aspect 32] 32. The composition of embodiment 31, 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, aluminum trihydrate, polyvinyl chloride, fluorinated iodocarbons, fluorinated bromocarbons, trifluoroiodomethane, perfluoroalkylamines, bromofluoroalkylamines, and mixtures thereof. [Aspect 33] A heat transfer device comprising the composition of any one of embodiments 1-32. [Aspect 34] 34. The heat transfer device of claim 33, wherein the heat transfer device is a cooling device. [Aspect 35] 35. The heat transfer apparatus of claim 33 or 34, wherein the heat transfer apparatus comprises an ultra-low temperature cooling system, such as a blast freezer. [Aspect 36] 36. The heat transfer apparatus of any one of aspects 33 to 35, wherein the heat transfer apparatus comprises a cascade system. [Aspect 37] A method of cooling an article, comprising condensing a composition of any one of embodiments 1-32, and then evaporating the composition in the vicinity of the article to be cooled. [Aspect 38] A method of heating an article, comprising condensing a composition of any one of aspects 1-32 in the vicinity of the article to be heated, and thereafter evaporating the composition. [Aspect 39] 33. A method of extracting a substance from a biomass, comprising contacting the biomass with a solvent comprising the composition of any one of aspects 1-32, and separating the substance from the solvent. [Aspect 40] A method of cleaning an article, comprising contacting the article with a solvent comprising the composition of any one of aspects 1-32. [Aspect 41] 33. A method of extracting a material from an aqueous solution or a particulate solid matrix, comprising contacting the aqueous solution or the particulate solid matrix with a solvent comprising a composition according to any one of claims 1 to 32, and separating the material from the solvent. [Aspect 42] A method of retrofitting a heat transfer device, comprising removing an existing heat transfer composition and introducing a composition according to any one of embodiments 1-32. [Aspect 43] 43. The method of claim 42, wherein the heat transfer device is a cooling device, preferably a cryogenic cooling system. [Aspect 44] 44. The method of embodiment 43, wherein the cooling system cools the compartment to less than about -60°C, preferably less than about -70°C. [Aspect 45] 33. A method of reducing an environmental impact resulting from the operation of a product that includes an existing compound or composition, the method comprising at least partially replacing the existing compound or composition with a composition according to any one of claims 1 to 32. [Aspect 46] 11. A method for generating greenhouse gas emission credits, the method comprising: (i) replacing an existing compound or composition with a composition according to any one of Aspects 1-32, wherein the composition according to any one of Aspects 1-32 has a lower GWP than the existing compound or composition; and (ii) acquiring greenhouse gas emission credits for the replacement step. [Aspect 47] The method of embodiment 46, wherein use of the composition of the present invention results in a lower total equivalent warming impact and / or a lower life cycle carbon footprint than that achieved by use of the existing compound or composition. [Aspect 48] 46. ​​The method of embodiment 45, implemented on products in the fields of air conditioning, refrigeration, heat transfer, gas dielectrics, flame suppression, solvents, cleaning agents, local anesthetics, and expansion applications. [Aspect 49] 49. The method of claim 45 or 48, wherein the product is selected from a heat transfer device or a solvent, preferably a heat transfer device. [Aspect 50] 50. The method of claim 49, wherein the article is a heat transfer device, preferably a cryogenic cooling system. [Aspect 51] 51. The method of any one of aspects 45-50, wherein the existing compound or composition is a heat transfer composition, preferably wherein the heat transfer composition is a refrigerant selected from R-508A, R-508B, R-23, and R-13B1. [Aspect 52] 13. Any novel heat transfer composition substantially as hereinbefore described, optionally with reference to the examples.

Claims

1. 1. A composition comprising: (i) 20 to 40% by weight of 1,1-difluoroethene (vinylidene fluoride, R-1132a); (ii) 30 to 60% by weight of carbon dioxide (CO ２ , R-744) and (iii) 1 to 35% by weight of pentafluoroethane (R-125); (iv) 1 to 20% by weight of trifluoromethane (R-23); 16. A composition consisting essentially of:

2. 2. The composition of claim 1, wherein the R-1132a is present in an amount of 20 to 35 weight percent.

3. 3. The composition of claim 1 or 2, wherein the R-1132a is present in an amount of 25 to 35% by weight.

4. 4. The composition according to any one of claims 1 to 3, wherein the carbon dioxide is present in an amount of from 35 to 60% by weight.

5. The composition according to any one of claims 1 to 3, wherein the carbon dioxide is present in an amount of from 30 to 55% by weight.

6. The composition of claim 1, wherein the carbon dioxide is present in an amount of 35 to 50% by weight.

7. The composition of any one of claims 1 to 6, wherein the R-125 is present in an amount of from 5 to 30% by weight.

8. The composition of claim 1, wherein the R-125 is present in an amount of 10 to 25% by weight.

9. The composition of any one of claims 1 to 8, wherein the composition has a GWP of less than 3700.

10. The composition of any one of claims 1 to 9, wherein the composition is non-flammable.

11. The composition according to any one of claims 1 to 10, wherein the composition has a temperature gradient in an evaporator or condenser of less than 10 K.

12. The composition of claim 11, wherein the composition has a temperature gradient in an evaporator or condenser of less than 7 K.

13. The composition of claim 1, wherein the composition has a critical temperature greater than 0°C.

14. The composition of claim 13, wherein the composition has a critical temperature greater than 10°C.

15. The composition of claim 1, wherein the composition has a volumetric cooling capacity that is at least 90% of the volumetric cooling capacity of R-23 under equivalent cycle conditions.

16. The composition of claim 15, wherein the composition has a volumetric cooling capacity that is at least 95% of the volumetric cooling capacity of R-23 under equivalent cycle conditions.

17. The composition of any one of claims 1 to 16, wherein the composition has a cycle efficiency (coefficient of performance, COP) that is within 5% of the existing refrigerant fluid it replaces.

18. The composition of claim 1, wherein the composition has a compressor discharge temperature that is within 15 K of the compressor discharge temperature of R-23 at equivalent cycle conditions.

19. 19. A composition comprising a lubricant and the composition of any one of claims 1 to 18, wherein the lubricant is selected from mineral oil, silicone oil, polyalkylbenzene (PAB), polyol ester (POE), polyalkylene glycol (PAG), polyalkylene glycol ester (PAG ester), polyvinyl ether (PVE), poly(alpha-olefin), and combinations thereof.

20. The composition of claim 19, wherein the lubricant is selected from PAG or POE.

21. The composition of claim 20, wherein the composition further comprises pentane.

22. A composition comprising a stabilizer and the composition of any one of claims 1 to 21.

23. The composition of claim 22, wherein the stabilizer is selected from diene compounds, phosphates, phenolic compounds and epoxides, and mixtures thereof.

24. 24. A composition comprising a flame retardant and the composition of any one of claims 1 to 23, 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, aluminum trihydrate, polyvinyl chloride, fluorinated iodocarbons, fluorinated bromocarbons, trifluoroiodomethane, perfluoroalkylamines, bromofluoroalkylamines, and mixtures thereof.

25. 25. A heat transfer device comprising the composition of any one of claims 1 to 24, said heat transfer device comprising a cryogenic cooling system.

26. The heat transfer device of claim 25, wherein the ultra-low temperature cooling system is a blast freezer.

27. ​​A heat transfer device as described in claim 25 or 26, wherein the heat transfer device includes a cascade system.

28. 25. A method of cooling an article, comprising condensing a composition according to any one of claims 1 to 24 and then evaporating said composition in the vicinity of the article to be cooled.

29. 25. A method of heating an article, comprising condensing a composition according to any one of claims 1 to 24 in the vicinity of the article to be heated and thereafter evaporating the composition.

30. A method of retrofitting a heat transfer device, comprising the steps of removing an existing heat transfer composition and introducing a composition according to any one of claims 1 to 24.

31. 25. A method of reducing the environmental impact resulting from the operation of a product comprising an existing compound or composition, said method comprising at least partially replacing said existing compound or composition with a composition according to any one of claims 1 to 24, said method being carried out on products in the fields of air conditioning, refrigeration, heat transfer, gas dielectrics, fire suppression, solvents, cleaning agents, local anesthetics and expansion applications, said product being a heat transfer device.

32. The method of claim 31, wherein the existing compound or composition is a heat transfer composition.

33. The method of claim 32, wherein the heat transfer composition is a refrigerant selected from R-508A, R-508B, R-23 and R-13B1.

34. Use of a composition according to any one of claims 1 to 24 as a refrigerant, wherein the temperature reached by using said composition is below -60°C.

35. The use according to claim 34, wherein the temperature reached by using the composition is below -70°C.

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