Compositions

Abstract

To provide refrigerant compositions which are suitable for use as low-temperature refrigerant compositions, especially in a low-temperature stage of a cascade refrigeration system.SOLUTION: There is provided a composition of carbon dioxide (CO2, R-744), difluoromethane (R-32) and 1,1-difluoroethylene (R-1132a).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to compositions, more particularly to refrigerant compositions suitable for use as low temperature refrigerant compositions, especially in the low temperature stage of a cascade refrigeration system. [Background technology]

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

[0003] Refrigeration systems that maintain cooling temperatures below -60°C have traditionally used non-flammable refrigerants such as R-23 (trifluoromethane) or R-508 (an azeotropic mixture of R-23 and perfluoroethane, R-116) in the bottom stage of a two-stage cascade refrigeration system. In this configuration, the low-temperature refrigerant evaporates at low temperatures (below -50°C) and is then compressed and condensed against the two-stage refrigerant loop at intermediate temperatures (usually in the range of -40°C to 0°C). Both R-23 and R-508 refrigerants have very high global warming potentials (GWPs). Therefore, it is desirable to find alternative refrigerants that can operate in this temperature range.

[0004] Ethane (R-170) is currently used in place of R-508 in certain very low temperature systems, particularly laboratory freezers for storing biomedical materials at temperatures below approximately -80°C. However, its extreme flammability prevents its safe use in larger systems such as those found in cryoblast freezing systems, climate chamber (wind tunnel) temperature control systems, larger biomedical refrigeration systems, food refrigeration systems, and very low temperature frozen food shipping containers.

[0005] Pure CO2 (R-744) has a low GWP and is non-flammable, but its triple point of -57°C means that it cannot be used alone in systems operating below about -55°C without forming solid dry ice on the low-pressure side of the refrigeration loop.

[0006] Binary mixtures of R-744 with several hydrofluorocarbon refrigerants, such as a binary mixture of R-744 with R-32, have been proposed as potential refrigerants suitable for low-temperature cascade refrigeration applications (di Nicola et al., Int J Refrig 28 (2005) 130-140, the contents of which are incorporated by reference in their entirety). However, the proposed R-744 / R-32 mixture (50 / 50 mass% R-744 / R-32) has a very large "temperature glide" in evaporation and condensation of approximately 15 K. This would make the use of heat exchangers designed for use with low-glide refrigerants, such as R-23, problematic and would require extensive redesign of the equipment. Furthermore, the compressor discharge temperatures of such binary mixtures would be significantly higher than those achieved with R-23 or R-508, also requiring potential redesign. Finally, the GWP of this mixture would still be relatively high (approximately 338 K). Summary of the Invention

[0007] The present invention addresses the above deficiencies and needs by providing a composition comprising carbon dioxide (CO2, R-744), difluoromethane (R-32), and 1,1-difluoroethylene (R-1132a), such a composition being hereinafter referred to as the composition of the present invention.

[0008] The present inventors have unexpectedly discovered that compositions including R-744, R-32, and R-1132a typically have operating characteristics similar enough to R-23 (so that the compositions are suitable for use in existing thermal equipment designs), while at the same time having a low GWP (e.g., less than 150), being less flammable compared to R-170, and typically being able to operate well below the triple point of R-744.

[0009] In particular, the compositions of the present invention provide a surprising combination of desirable properties, such as minimal flammability, a good performance match with R-23 at similar operating pressures, low temperature glide, and acceptable compressor discharge temperatures. The compositions of the present invention preferably solidify (i.e., form dry ice) during operation at temperatures below about -70°C, and even below about -75°C. Thus, the compositions can be used at operating temperatures below the triple point temperature of CO2 without forming dry ice during operation.

[0010] Furthermore, the compositions of the present invention have been found to be particularly suitable for use as replacements or substitutes for existing refrigerants such as R-23 or R-508. The compositions of the present invention are particularly advantageous in the low temperature stage of cascade refrigeration systems. The compositions of the present invention are also suitable for use in low temperature blast freezing systems, climate chamber (wind tunnel) temperature control systems, biomedical refrigeration systems, food refrigeration systems, ultra-low temperature frozen food shipping containers, and similar heat transfer systems. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a graph showing the solubility of solid R-744 in R-1132a. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will now be described in detail.

[0013] According to the present invention, there is provided a composition comprising carbon dioxide (CO2, R-744), difluoromethane (R-32), and 1,1-difluoroethylene (R-1132a).

[0014] Typically, the compositions of the present invention comprise from about 1 to about 40 or about 30 wt %, for example, from about 1 to about 25 or about 22 wt %, for example, from about 2 or about 3 to about 20 wt %, optionally from about 4 to about 18 or about 20 wt %, of R-32.

[0015] Advantageously, the compositions of the present invention comprise at least about 35% by weight CO2, such as at least about 37 or at least about 40% by weight, such as at least about 42% by weight or at least about 45% by weight.

[0016] Advantageously, the composition comprises about 38 to about 70% by weight CO2, such as about 40 to about 65% by weight, for example about 42 to about 62% by weight, optionally about 44 to about 60% by weight or about 46 to about 58% by weight.

[0017] Advantageously, the composition comprises at least about 28% by weight, such as at least about 30% by weight, for example, at least about 32 or at least about 34% by weight, preferably at least about 35 or at least about 37% by weight, optionally at least about 39 or at least about 40% by weight, of R-1132a.

[0018] Typically, the compositions of the present invention contain about 29% to about 55% by weight, such as about 31 to about 52% by weight, for example, about 34 to about 49% by weight or about 35 to about 47% by weight, of R-1132a.

[0019] Advantageously, the compositions of the present invention comprise from about 30 to about 70 wt. % CO2, from about 1 to about 25 wt. % R-32, and from about 28 to about 50 wt. % R-1132a, such as from about 35 to about 65 wt. % CO2, from about 2 to about 22 wt. % R-32, and from about 30 to about 48 wt. % R-1132a. 、 For example, it contains about 40 to about 60% by weight of CO2, about 3 to about 20% by weight of R-32, and about 32 to about 46% by weight of R-1132a.

[0020] The composition of the present invention may additionally contain an additional component selected from monofluoromethane (R-41), pentafluoroethane (R-125), trifluoroethylene (R-1123), 1,1,1,2-tetrafluoroethane (R-134a), 1,1-difluoroethane (R-152a), 2,3,3,3-tetrafluoropropene (R-1234yf), trans-1,3,3,3-tetrafluoropropene (R-1234ze(E)), and mixtures thereof. One advantage of adding an additional component to the composition is that the additional component can help further lower the solid CO onset temperature.

[0021] Advantageously, the further component is present in the composition in an amount of from about 1 to about 10% by weight, such as from about 1 to about 8% by weight, for example from about 2 to about 6% by weight or from about 3 to about 5% by weight.

[0022] Typically, the further component is selected from R-134a, R-152a, R-1234yf and R-1234ze(E) and mixtures thereof, preferably in an amount of from about 1 to about 5 wt %. Conveniently, the further component is R-134a.

[0023] In some embodiments, when the additional component is R-134a, R-1234yf, R-152a, R-1234ze(E), or a mixture thereof, the additional component is present in the composition of the present invention in an amount of less than about 5% by weight.

[0024] The compositions of the present invention may further comprise one or more hydrocarbons. One advantage of including a hydrocarbon in the compositions of the present invention is that it can aid in oil return at low operating temperatures when the compositions are used in heat transfer systems.

[0025] For example, hydrocarbons may be present in the compositions of the present invention in an amount of from about 1 to about 5 weight percent, such as from about 1 or about 2 to about 4 weight percent.

[0026] Advantageously, the hydrocarbon is selected from propane (R-290), isobutane (R-600a), ethane (R-170) and mixtures thereof.

[0027] In a preferred embodiment, the compositions of the present invention comprise CO2 and R-1132a in a weight ratio of about 1:1 to about 2.5:1, such as about 1.05:1 to about 2:1, such as about 1.1:1 to about 1.6:1.

[0028] Thus, the compositions of the present invention are about 2 to about 20 wt. % R-32 and about 80 to about 98 wt. % CO2 and R-1132a (optionally about 4 to about 18 wt. % R-32 and about 82 to about 96 wt. % R-1132a and CO2), wherein the weight ratio of CO2 to R-1132a is about 1:1 to about 2:1, e.g., about 1.05:1 to about 2:1, e.g., about 1.1:1 to about 1.6:1.

[0029] In one embodiment, the composition is classified as mildly flammable ("Class 2L") as determined by ASHRAE Standard 34:2019. Advantageously, the composition has a burning velocity of less than about 10 cm / sec, e.g., less than about 9 cm / sec, e.g., less than about 8 cm / sec.

[0030] Flammability may be determined by ASHRAE Standard 34, which incorporates ASTM Standard E-681 (e.g., ASHRAE Standard 34:2019), the entire contents of which are incorporated herein by reference.

[0031] In one embodiment, the composition has one or more of: (a) a higher lower flammability limit; (b) a higher ignition energy; (c) a higher autoignition temperature; or (d) a lower burn rate compared to R-1132a alone.

[0032] Preferably, the compositions of the present invention are less flammable than R-1132a in one or more of the following: lower flammability limit at 23°C, lower flammability limit at 60°C, width of flammable range at 23°C or 60°C, autoignition temperature (thermal decomposition temperature), minimum ignition energy in dry air, or burning rate. The flammability limit and burning rate are determined according to the method specified in ASHRAE-34, and the autoignition temperature is determined in a 500 ml glass flask according to the method of ASTM E659-78.

[0033] The inventors have found that compositions of the present invention having a mass ratio of R-744 to R-1132a of about 1.1:1 or greater (preferably from about 1.05:1 to about 2:1, e.g., from about 1.1:1 to about 1.6:1) have laminar burning velocities of about 10 cm / sec (or less), which is the threshold requirement for classifying a refrigerant as "slightly flammable" (Flammability Class 2L) according to the ASHRAE Standard 34 process.

[0034] In one embodiment, the composition can consist essentially of the recited components. By the term "consisting essentially of," we include the meaning that the composition is substantially free of other components, particularly additional (hydro)(fluoro) compounds (e.g., (hydro)(fluoro)alkanes or (hydro)(fluoro)alkenes) known to be used in heat transfer compositions. The term "consisting of" is included in the meaning of "consisting essentially of."

[0035] In one embodiment, the composition is substantially free of any components (other than those specified) that have heat transfer properties. For example, the composition of the present invention may be substantially free of any other hydrofluorocarbon compounds.

[0036] In one embodiment, the compositions of the present invention are substantially free of trifluoroiodomethane (CF3I).

[0037] In another embodiment, the compositions of the present invention are substantially free of trifluoroethylene (R-1123).

[0038] "Substantially free" and "substantially free" include meaning that the composition contains no more than 0.5% by weight, preferably no more than 0.4%, 0.3%, 0.2%, or 0.1% of the above constituents, based on the total weight of the composition.

[0039] The compositions of the present invention have an ozone depletion potential of zero.

[0040] Advantageously, the compositions of the present invention have a global warming potential (GWP) of less than about 200, such as less than about 170, for example less than about 150 or about 140.

[0041] The compositions disclosed herein are believed to exhibit a completely unexpected combination of low / non-flammability, low GWP, and improved refrigeration performance properties at low temperatures, some of which are described in more detail below.

[0042] Typically, the compositions of the present invention have a volumetric cooling capacity within about 20% or about 25%, such as within about 15%, e.g., within about 10%, of the volumetric cooling capacity of R-23. For example, the compositions have a volumetric cooling capacity of about 90 to about 120% of the volumetric cooling capacity of R-23.

[0043] Advantageously, the composition has a coefficient of performance (COP) that is within about 10% or 7%, such as within about 5%, such as within about 4%, of the COP of R-23.

[0044] Advantageously, the composition has a temperature glide in the condenser or evaporator of less than about 15K, such as less than about 12K, for example less than about 10K, preferably less than about 8K.

[0045] Typically, the composition has a compressor discharge temperature that is less than about 140°C, such as less than about 130°C, for example, less than about 120°C or about 110°C.

[0046] Advantageously, the composition has an operating pressure in the condenser that is 2 bar ±20% (of the pressure value), such as 2 bar ±10%.

[0047] Advantageously, the composition has an operating pressure in the evaporator that is 0.5 bar ±20% (of the pressure value), such as 0.5 bar ±10%.

[0048] Typically, the compositions do not solidify during operation at temperatures above about −70° C., such as above about −75° C. This allows the compositions of the present invention to operate efficiently in low temperature heat transfer systems.

[0049] Preferably, the composition has a pressure ratio for the compressor that is within about 20%, such as within about 10%, of the pressure ratio of R-23.

[0050] In another aspect of the present invention, there is provided the use of the composition of the present invention as a working fluid in a heat transfer system.

[0051] Conveniently, the heat transfer system is a refrigeration system, such as a cascade refrigeration system.

[0052] Advantageously, the heat transfer system is selected from a cryoblast freezing system, a climate chamber (eg, wind tunnel) temperature control system, a biomedical refrigeration system, a food refrigeration system, and a cryogenically frozen food transport container.

[0053] A further aspect of the present invention provides the use of the composition of the present invention as a replacement for an existing working fluid in a heat transfer system, typically R-23 or R-508.

[0054] In another aspect of the present invention there is provided a heat transfer system comprising the composition of the present invention. Conveniently the heat transfer system is a (low temperature) refrigeration system such as a cascade refrigeration system.

[0055] Typically, the heat transfer system is selected from a cryoblast freezing system, a climate chamber (eg, wind tunnel) temperature control system, a biomedical refrigeration system, a food refrigeration system, and a cryogenically frozen food transport container.

[0056] According to a further aspect, there is provided a method of producing cooling comprising evaporating a composition of the present invention in the vicinity of a body to be cooled.

[0057] In another aspect of the present invention, there is provided a method for producing heating comprising condensing or cooling a composition of the present invention in the vicinity of a body to be heated.

[0058] 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.

[0059] The term "about" when used in connection with numerical values ​​of amounts of components in weight percent includes a meaning of ±0.5 weight percent, for example ±0.2 weight percent.

[0060] For the avoidance of doubt, it is to be understood that the upper and lower limits set forth for ranges of the amounts of components in the compositions disclosed herein can be interchanged in any manner so long as the resulting range falls within the broadest scope of the invention.

[0061] The composition can be prepared by simply mixing CO2, R-32 and R-1132a with optional components such as additional components (e.g., R-134a) and / or lubricants.

[0062] All chemicals described herein are commercially available, for example, fluorochemicals are available from Apollo Scientific (UK).

[0063] The invention is illustrated by the following non-limiting examples. [Example]

[0064] The laminar burning velocity of mixtures of R-1132a and R-744 was tested using the Jabbour vertical tube method referenced in ASHRAE Standard 34. The laminar burning velocity of R-32 is 6.7 cm / sec, and compositions of the present invention are expected to have an overall burning velocity of less than 10 cm / sec.

[0065] The binary vapor-liquid equilibria of R-1132a and R-744 and R-1132a and R-32 were studied in constant-volume cells at temperatures ranging from -70°C to 10°C. The general experimental method consisted of measuring the vapor pressure of a known binary mixture composition over a temperature range to generate a pressure-temperature-composition data set. The data were then regressed to a thermodynamic model capable of representing both vapor-liquid and solid-liquid equilibria. The model used was the Peng-Robinson equation of state using the Wong and Sandler mixing rule, and the liquid-phase free energy was correlated with the NRTL model (hereafter referred to as the PRWS / NRTL model).

[0066] At temperatures below the triple point of R-744, the formation of solid CO2 was observed at high CO2 concentrations in the binary R-1132a / CO2 system. The Schroeder equation, along with NRTL equation parameters fitted to the VLE data, was used to predict the liquid composition in equilibrium with solid CO2 at these temperatures. Excellent agreement with experiment was found for the observed onset of solid formation, as shown in Figure 1.

[0067] Vapor-liquid equilibrium data available in the literature for R-744 with R-32 were fitted to the same PRWS / NRTL model, and the resulting NRTL parameters were then used to estimate the solubility of solid R-744 in fluorocarbon mixtures at temperatures below the triple point of R-744.

[0068] Thermodynamic cycle models were then constructed in the Matlab programming environment using standard cycle modeling techniques. The models used the PRWS / NRTL framework with additional codes to estimate the onset temperature of solid R-744 formation for each composition investigated. The compositions were modeled relative to R-23 as the reference fluid.

[0069] Table 1 shows selected cycle conditions, which are believed to represent the operating conditions in the low temperature stage of a very low temperature frozen food transport system. [Table 1]

[0070] The performance of selected compositions of the present invention is shown below in Tables 2 and 3 using R-23 as the reference fluid. Table 4 shows the estimated solid formation temperatures of compositions of the present invention further containing R-134a.

[0071] The performance data indicates that the performance of the compositions of the present invention is acceptably close to that of R-23. For example, the compositions of the present invention preferably exhibit one or more of the following performance characteristics: -Volumetric cooling capacity is approximately 90% to 120% of the volumetric cooling capacity of R-23 Coefficient of performance (energy efficiency) within approximately 5% of that of R-23 Temperature glide below approximately 10K Compressor discharge temperature is less than approximately 130°C Similar pressure ratio to the compressor as R-23 (which translates to similar volumetric efficiency) Operating pressure of approximately 2 bar on the condenser and approximately 0.5 bar on the evaporator Solid formation temperature below approximately -70°C Global warming potential less than 150

[0072] Performance data also shows that decreasing the weight ratio of R-744 to R-1132a increases the burning rate but decreases the glide, discharge temperature, and solid dry ice onset temperature. [Table 2] [Table 3] [Table 4]

[0073] The present invention includes the following aspects. [Aspect 1] (a) Carbon dioxide (CO2, R-744), (b) Difluoromethane (R-32), and (c) A composition comprising 1,1-difluoroethylene (R-1132a). [Aspect 2] 2. The composition of embodiment 1, comprising from about 1 to about 40 or 30 wt. %, e.g., from about 1 to about 25 or about 22 wt. %, e.g., from about 2 or about 3 to about 20 wt. %, optionally from about 4 to about 18 or about 20 wt. % R-32. [Aspect 3] 3. The composition of any one of the preceding claims, comprising at least about 35% by weight CO2, e.g., at least about 37% by weight or at least about 40% by weight CO2, e.g., at least about 42% by weight or at least about 45% by weight CO2. [Aspect 4] The composition of any one of claims 1 to 3, comprising at least about 28 wt. % R-1132a, e.g., at least about 30 wt. %, e.g., at least about 32 or at least about 34 wt. %, preferably at least about 35 or at least about 37 wt. %, and optionally at least about 39 or at least about 40 wt. % R-1132a. [Aspect 5] The composition of any one of aspects 1 to 4, comprising about 38 to about 70 wt. % CO2, e.g., about 40 to about 65 wt. %, e.g., about 42 to about 62 wt. %, optionally about 44 to about 60 wt. % or about 46 to about 58 wt. % CO2. [Aspect 6] 6. The composition of any one of aspects 1 to 5, comprising about 29% to about 55% by weight, such as about 31 to about 52% by weight, for example, about 34 to about 49% by weight or about 35 to about 47% by weight, of R-1132a. [Aspect 7] About 30 to about 70% by weight of CO2, about 1 to about 25% by weight of R-32, and about 28 to about 50% by weight of R-1132a, for example, about 35 to about 65% by weight of CO2, about 2 to about 22% by weight of R-32, and about 30 to about 48% by weight of R-1132a 、 For example, the composition according to any one of aspects 1 to 6, comprising about 40 to about 60 wt% CO2, about 3 to about 20 wt% R-32, and about 32 to about 46 wt% R-1132a. [Aspect 8] Aspect 8. The composition of any of aspects 1-7, wherein the composition additionally comprises a further component selected from monofluoromethane (R-41), pentafluoroethane (R-125), trifluoroethylene (R-1123), 1,1,1,2-tetrafluoroethane (R-134a), 1,1-difluoroethane (R-152a), 2,3,3,3-tetrafluoropropene (R-1234yf), trans-1,3,3,3-tetrafluoropropene (R-1234ze(E)), and mixtures thereof. [Aspect 9] The composition of embodiment 8, wherein the additional component is present in the composition in an amount of from about 1 to about 10% by weight, e.g., from about 1 to about 8% by weight, e.g., from about 2 to about 6% by weight, or from about 3 to about 5% by weight. [Aspect 10] 10. The composition of claim 8 or 9, wherein the additional component is selected from R-134a, R-152a, R-1234yf, and R-1234ze(E), and mixtures thereof, preferably in an amount of about 1 to about 5 wt. %, e.g., the additional component is R-134a. [Aspect 11] 11. The composition of any one of aspects 1-10, wherein the composition additionally comprises a hydrocarbon. [Aspect 12] 12. The composition of embodiment 11, wherein the hydrocarbon is present in an amount of about 1 to about 5 wt. %, such as about 1 or about 2 to about 4 wt. %. [Aspect 13] 13. The composition of any one of aspects 11 to 12, wherein the hydrocarbon is selected from propane (R-290), isobutane (R-600a), ethane (R-170), and mixtures thereof. [Aspect 14] 14. The composition of any one of aspects 1 to 13, comprising the CO2 and the R-1132a in a weight ratio of about 1.05:1 to about 2:1, such as about 1:1 to about 2.5:1, for example about 1.1:1 to about 1.6:1. [Aspect 15] 15. The composition of any of aspects 1-14, consisting essentially of the previously described components. [Aspect 16] 16. The composition of any of the preceding aspects, wherein the composition is classified as slightly flammable ("Class 2L") as determined by ASHRAE Standard 34:2019, and / or the composition has a burn velocity of less than about 10 cm / sec, e.g., less than about 8 cm / sec, such as less than about 9 cm / sec. [Aspect 17] Aspect 17. The composition of any of aspects 1-16, wherein the composition has a Global Warming Potential (GWP) of less than about 200, such as less than about 170, for example less than about 150. [Aspect 18] 18. The composition of any of aspects 1-17, wherein the composition has a volumetric cooling capacity within about 15%, such as within about 20% or about 25%, e.g., within about 10%, of the volumetric cooling capacity of R-23. [Aspect 19] Aspect 19. The composition of any of aspects 1-18, wherein the composition has a coefficient of performance (COP) that is within about 7%, such as within about 10%, e.g., within about 5%, of the COP of R-23. [Aspect 20]

[0033] Aspect 20. The composition of any of aspects 1-19, wherein the composition has a temperature glide in a condenser or evaporator of less than about 15 K, such as less than about 12 K, for example, less than about 10 K, preferably less than about 8 K. [Aspect 21] 21. The composition of any of the preceding aspects, wherein the composition has a compressor discharge temperature that is less than about 140°C, such as less than about 130°C, e.g., less than about 120°C or about 110°C. [Aspect 22] 22. The composition of any of the preceding aspects, wherein the composition has an operating pressure in the condenser that is 2 bar ± 20%, such as 2 bar ± 10%. [Aspect 23] 23. The composition of any of the preceding aspects, wherein the composition has an operating pressure in an evaporator that is 0.5 bar ± 20%, such as 0.5 bar ± 10%. [Aspect 24] 24. The composition of any of aspects 1-23, wherein the composition does not solidify during operation at temperatures of about −70° C. or higher, such as about −75° C. or higher. [Aspect 25] 25. The composition of any one of aspects 1-24, wherein the composition has a pressure ratio to the compressor that is within about 20%, such as within about 10%, of the pressure ratio to the compressor of R-23. [Aspect 26] 26. Use of the composition according to any one of aspects 1 to 25 as a working fluid in a heat transfer system. [Aspect 27] 27. The use according to aspect 26, wherein the heat transfer system is a refrigeration system, such as a cascade refrigeration system. [Aspect 28] 28. The use of aspect 26 or 27, wherein the heat transfer system is selected from a cryoblast freezing system, a climate chamber (e.g., wind tunnel) temperature control system, a biomedical refrigeration system, a food refrigeration system, and a cryogenically frozen food transport container. [Aspect 29] 27. Use of a composition as defined in any of aspects 1-26 as a replacement for an existing working fluid in a heat transfer system, where the existing working fluid is R-23 or R-508. [Aspect 30] A heat transfer system comprising the composition of any one of embodiments 1 to 26. [Aspect 31] 31. The heat transfer system of embodiment 30, wherein the heat transfer is selected from a cryogenic blast freezing system, a climate chamber (e.g., wind tunnel) temperature control system, a biomedical refrigeration system, a food refrigeration system, and a cryogenically frozen food transport container. [Aspect 32] A method of producing cooling, comprising evaporating the composition of any of embodiments 1-26 in the vicinity of a body to be cooled. [Aspect 33] A method for producing heating is provided, comprising condensing or cooling the composition of any of embodiments 1-26 in the vicinity of a body to be heated.

Claims

[Claim 1] (a) Carbon dioxide (CO ２ , R-744), (b) difluoromethane (R-32), and (c) A composition comprising 1,1-difluoroethylene (R-1132a).

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