Refrigerant composition

Abstract

The present invention provides a refrigerant composition that improves the efficiency of a transcritical refrigeration system using carbon dioxide. [Solution] A refrigerant composition comprising, based on the total weight of the refrigerant composition, 50 to 95% by weight of carbon dioxide (CO2, R-744), 1 to 25% by weight of difluoromethane (R-32), 2 to 15% by weight of 1,1-difluoroethylene (R-1132a), and a tetrafluoropropene selected from 2,3,3,3-tetrafluoropropene (R-1234yf) and 1,3,3,3-tetrafluoropropene (R-1234ze(E)).

Description

Technical Field

[0001] The present invention relates to a refrigerant composition, and more specifically, to a refrigerant composition containing carbon dioxide (CO2, R-744) useful in a transcritical refrigeration cycle. Specifically, the present invention relates to a refrigerant composition containing carbon dioxide useful in an automotive air conditioning and heat pump system utilizing a transcritical refrigeration cycle, particularly a system for electric vehicles.

Background Art

[0002] 1,1,1,2-Tetrafluoroethane (R-134a) was the refrigerant selected for several years in automotive air conditioning systems following the phased-out of dichlorodifluoromethane (R-12), a CFC, and has a high ozone depletion potential. Subsequently, the EU F-gas regulation was implemented, imposing a global warming potential (GWP) limit of 150 on new vehicle mobile air conditioning (MAC) systems. As a result, the use of R-134a has been largely replaced in new European systems by the use of flammable 2,3,3,3-tetrafluoropropene (R-1234yf). R-1234yf is slightly less efficient than R-134a, and new system designs currently include additional equipment (internal heat exchangers) to recover the loss of efficiency.

[0003] Mobile air conditioning systems using carbon dioxide in a transcritical vapor compression refrigeration cycle are known. Since the global warming potential of carbon dioxide is 1, it is an acceptable refrigerant according to the EU F-gas regulation.

[0004] The basic transcritical cycle consists of the following steps: 1. Evaporation of the liquid refrigerant at low pressure and removal of heat from a low-temperature source fluid (such as air), 2. Compressing the refrigerant vapor obtained by the compressor to generate a high-temperature high-pressure gas, 3. Generating a high-pressure, lower-temperature, and higher-density refrigerant gas by cooling the high-pressure gas through heat exchange with a sink fluid at a temperature higher than the source. Since this gas exceeds the critical temperature, it is called a "supercritical" fluid, and 4. The expansion of the supercritical fluid via an expansion valve or other limiting device yields a two-phase mixture of liquid refrigerant and vaporized refrigerant vapor at low pressure, which is then fed back to the evaporator stage to complete the cycle.

[0005] In some systems that utilize carbon dioxide in a transcriticality refrigeration cycle, compression is performed in two stages. This can improve cycle efficiency by cooling the gas between the two compression stages.

[0006] The performance, particularly the efficiency, of transcritical refrigeration cycles using carbon dioxide is typically lower than that of conventional subcritical cycles using R-134a or similar materials operating between the same source and sink temperatures.

[0007] It would be desirable to improve the efficiency of transitional criticality refrigeration systems that use carbon dioxide. [Disclosure of the Invention]

[0008] Unexpectedly, it was found that adding difluoromethane (R-32) and optionally one or more additional fluorinated refrigerants to carbon dioxide could improve the efficiency of transcritical refrigeration systems and reduce the operating pressure of such systems. The refrigerants can also meet the 150 GWP limit set by the EU F-gas regulations and are non-flammable.

[0009] Therefore, in a first aspect, the present invention provides a refrigerant composition comprising carbon dioxide (CO2, R-744) and 1 to 32% by weight of difluoromethane (R-32) based on the total weight of the refrigerant composition.

[0010] Preferably, the refrigerant composition of the present invention contains 1 to 25% by weight of R-32, for example, about 2 to about 22%, based on the total weight of the refrigerant composition.

[0011] It has been found that adding R-32 to carbon dioxide can increase the fluid's energy efficiency compared to pure carbon dioxide when used in a transcritical vapor compression cycle developed for using carbon dioxide as a refrigerant in various applications. The refrigerant composition of the present invention preferably has a global warming potential of less than 150 and is preferably non-flammable.

[0012] In one embodiment, difluoromethane is present in an amount of 20–25% by weight based on the total weight of the refrigerant composition. This amount of R-32 balances the cycle characteristics while maintaining an acceptable level of temperature glide. In another embodiment, difluoromethane is present in an amount of less than 22% by weight, for example, less than 21% by weight, based on the total weight of the refrigerant composition.

[0013] A particular composition of the present invention is a binary refrigerant composition comprising 75-99% by weight of carbon dioxide and 25-1% by weight of difluoromethane. A preferred binary refrigerant composition comprises 75-80% by weight of carbon dioxide and 25-20% by weight of difluoromethane. One preferred binary refrigerant composition comprises 78% by weight of carbon dioxide ±1% by weight and 22% by weight of difluoromethane ±1% by weight. Another preferred binary refrigerant composition comprises 79% by weight of carbon dioxide ±1% by weight and 21% by weight of difluoromethane ±1% by weight. A binary refrigerant composition containing less than 22% by weight of difluoromethane has a GWP of less than 150.

[0014] A binary composition of R-32 and carbon dioxide at up to approximately 22% by weight can exhibit the following advantages: improved energy efficiency compared to carbon dioxide, reduced operating pressure compared to carbon dioxide, temperature glide in the evaporator below 10°C, and a global warming potential of less than 150, which is a requirement for European automotive air conditioning and some stationary refrigeration / air conditioning systems subject to European F-gas regulations.

[0015] In one embodiment of the present invention, the composition may further contain 1,1-difluoroethylene (R-1132a).

[0016] In one embodiment, R-1132a is present in the composition of the present invention in an amount of up to 20 or 22% by weight, for example, 2 to 15% by weight, preferably 4 to 14% by weight, based on the total weight of the refrigerant composition.

[0017] Conveniently, such compositions of the present invention, based on the total weight of the refrigerant composition, contain 50 to 95% by weight of carbon dioxide, 1 to 32% by weight of difluoromethane, and 1 to 20% by weight of R-1132a, for example 55 to 93% by weight of carbon dioxide, 2 to 32% by weight of difluoromethane, and 2 to 15% by weight of R-1132a, preferably 64 to 93% by weight of carbon dioxide, 2 to 25% by weight of difluoromethane, and 2 to 14% by weight of R-1132a, for example 65 to 93% by weight of carbon dioxide, 2 to 22% by weight of difluoromethane, for example 2 to 14% by weight of R-1132a.

[0018] Preferred compositions of the present invention further include 1,1,1,2-tetrafluoroethane (R-134a). The ratio of R-32 to R-134a in the composition is preferably selected such that the entire composition is considered non-flammable at the time of formulation, is considered non-flammable according to the ASHRAE Standard 34 protocol, and has a global warming potential (GWP) of less than 150. These preferred compositions are particularly suitable for use in automotive air conditioning and heat pump applications, among other applications.

[0019] In another embodiment of the present invention, the ratio of R-32 to R-134a in the composition is selected such that the overall composition is non-flammable according to the ASHRAE Standard 34 protocol and has a global warming potential (GWP) of less than 300. These preferred compositions are considered suitable for use in stationary refrigeration applications.

[0020] A preferred ternary composition contains 86% by weight of carbon dioxide ±1% by weight, 7% by weight of difluoromethane ±1% by weight, and 7% by weight of 1,1,1,2-tetrafluoroethane ±1% by weight.

[0021] Another preferred refrigerant composition of the present invention is a quaternary composition comprising carbon dioxide, difluoromethane, R-1132a, and 1,1,1,2-tetrafluoroethane.

[0022] The refrigerant compositions of the present invention may also include other refrigerant compounds in place of or in addition to 1,1,1,2-tetrafluoroethane (R-134a) used in the above ternary compositions in order to provide other ternary or higher refrigerant compositions. Suitable refrigerant compounds to be included in the refrigerant compositions of the present invention include 2,3,3,3-tetrafluoropropene (R-1234yf) and 1,3,3,3-tetrafluoropropene (R-1234ze(E)). When R-1234yf or R-1234ze(E) is used in addition to R-134a in the composition, the amount of the compound is preferably selected such that the binary mixture with either R-1234yf or R-1234ze(E)e is non-flammable.

[0023] In one embodiment, the composition of the present invention may consist essentially of the components described. The term "essentially consisting of" means that the composition of the present invention substantially does not contain other components, in particular further (hydro)(fluoro) compounds (e.g., (hydro)(fluoro)alkanes or (hydro)(fluoro)alkenes) that are known to be used in heat transfer compositions. The term "consisting of" is included in the meaning of "essentially consisting of".

[0024] "Substantially absent" means that the composition of the present invention contains 0.5% by weight or less, preferably 0.1% by weight or less, of the described component based on the total weight of the refrigerant composition.

[0025] The compositions of the present invention are useful in mobile air conditioning applications and mobile heat pump applications using transitional criticality refrigeration cycles. The compositions may offer particular benefits when air conditioning and / or heat pump systems are used in electric vehicles, whether purely electric or hybrid vehicles.

[0026] Thus, in a second aspect, the present invention provides a transcritical air conditioning and / or heat pump system that uses the refrigerant composition of the first aspect of the present invention. The refrigerant composition can be as described in any of the above embodiments.

[0027] Transcritical cycle technology is also used with carbon dioxide in the following applications: heat pump water heaters for generating domestic hot water, refrigeration of supermarkets at medium and low temperature levels, residential air conditioning, and refrigerated transport systems. In some of these applications, the vapor compression cycle used is a single compression cycle common for mobile air conditioning. In other applications, gas compression is performed in two stages, enabling efficient operation for large temperature differences between the heat source and the heat sink. Thus, the composition is suitable for use in single and double compression stage cycles.

[0028] The refrigerant composition of the present invention is typically combined with a lubricant when used in a refrigeration, air conditioning, or heat pump system. Suitable lubricants include polyol esters such as neopentyl polyol esters, and polyalkylene glycols, preferably end-capped with alkyl groups at both ends, for example, C 1~4 alkyl groups.

Examples

[0029] The present invention will now be illustrated by the following examples, but the present invention is not limited by the examples.

[0030] Example 1 The performance of transitional criticality air conditioning cycles for mobile air conditioning (MAC) applications was investigated using standard vapor compression cycle modeling techniques. The thermodynamic properties of the mixtures were calculated using REFPROP 9.1 characterization software. Default REFPROP interaction parameters for CO2 and R-32 mixtures were used in all calculations. For mixtures containing R-134a, CO2, and R32, REFPROP interaction parameters were used for the R-32 / R-134a pair, and experimentally derived interaction parameters were used for the CO2 / R-134a pair.

[0031] First, a cycle using a single-stage compressor was simulated under conditions representative of automotive air conditioning applications. As is typical of transcritical CO2 systems, the suction line / high-pressure gas heat exchanger was included in the cycle. The simulated cycle is schematically shown in Figure 1.

[0032] The following cycle parameters were used: [Table 1]

[0033] The model did not take into account the pressure drop across the system components.

[0034] The cycle model was implemented in Microsoft Excel. In the cycle calculation, the evaporator pressure was varied so that the calculated average evaporation temperature met the target value. Simultaneously, the gas cooler pressure was varied to maximize the cycle's coefficient of performance (COP).

[0035] A binary mixture of CO2 and R32 was simulated across various compositions at three different ambient temperatures. The results are shown in Table 2 below, and selected data are graphed in Figures 2–5. [Table 2]

[0036] The following trends can be observed. A performance-enhancing coefficient, such as that used for R-32, is added to CO2. The degree of improvement depends on the ambient temperature experienced by the gas cooler. • When R-32 is added, the optimal operating pressure of the gas cooler decreases, which is advantageous for the compressor. When R-32 is added, the volumetric capacity decreases slightly, and in a blend with 21% R32, it drops to about 85% of pure CO2. • As the R-32 content increases, the evaporator temperature glide increases. For compositions with a GWP of less than 150 (<22 wt% R-32), the evaporator glide is less than 6°C and should have little adverse effect on evaporator performance.

[0037] It is clear that adding R-32 in amounts less than 22% by weight can improve the energy efficiency of the cycle and significantly reduce the operating pressure.

[0038] Example 2 Next, the performance of R-32 / CO2 blends in automotive heat pump cycles was investigated using cycle modeling. The heat pump cycle is used in battery-powered electric vehicles (pure electric and hybrid powertrains). The cycle model from the previous example was used, with parameters modified as shown in Table 3. These were selected to represent the conditions of automotive applications.

[0039] The following cycle parameters were used: [Table 3]

[0040] The selected results are shown in Figures 6-9. In this process, COP refers to the coefficient of merit of the heating mode.

[0041] In heat pump mode, the same general trend of performance enhancement with the addition of R-32 occurs, so using an R-32 / CO2 blend improves energy efficiency and reduces operating pressure compared to using pure CO2. Improved energy efficiency is particularly important for heat pumps installed in electric vehicles, as it reduces the energy consumed for passenger comfort and extends the battery's effective range.

[0042] Example 3 The cycle model was constructed with a two-stage compression cycle in which the compressed gas undergoes intercooling after the initial compression stage, followed by the retention of liquid refrigerant in a flash tank held at interstage pressure. The modeled cycle is shown in Figure 10.

[0043] As shown in Table 4, cycle simulations for CO2 and selected R-32 / CO2 blends were performed using this cycle with the input parameters. [Table 4]

[0044] Figures 11-14 show the results selected for two levels of refrigeration: medium temperature (-5°C evaporator) and low temperature (-40°C evaporator).

[0045] In Figures 12-14, "Series 1" refers to "medium temperature" conditions.

[0046] When R-32 is added to carbon dioxide (CO2, R-744), the same performance trends as in the previous single-cycle modeling are observed in the two-cycle model. • Increased energy efficiency • Reduction of operating pressure • When the R-32 content is less than approximately 25% by weight, the temperature glide in the evaporator remains below 10K. • The addition of R-32 reduces the volumetric cooling capacity.

[0047] Example 4 Using REFLEAK4.0, we investigated vapor leakage of a 21% R-32 / 79% CO2 mixture under the worst-case conditions mandated by Standard 34, i.e., vapor leakage from an initially filled storage cylinder to 90% of the maximum permissible fill density at -40°C. If approximately 77% or more of the charge leaked, the remaining liquid in the cylinder was found to be flammable, as it contained more than 59% by weight of R-32.

[0048] When this procedure was repeated with a 10% R-32 / 90% CO2 mixture, it was found that after removing 90% of the charge as vapor at -40°C, it was also separated into a flammable liquid composition.

[0049] For consideration in the binary blend, fractions of the 86% CO2 mixture were investigated using NIST REFLEAK for the same cylinder leakage case with 7% R-32 and 7% R-134a. This configuration has 148 GWP. The binary interaction parameters of R-32 and CO2 and R-134a and CO2, derived by fitting experimental gas-liquid equilibrium data, were input into the model for this simulation.

[0050] The addition of R-134a to the blend was found to ensure that the vapor and liquid compositions remained non-flammable throughout the leak process. This is shown in Figure 15, which illustrates the trajectories of the liquid and gas phases during fractionation in a ternary composition diagram. The vertices of the triangle represent pure R-32, the lower left vertex is pure R-134a, and the lower right vertex is pure CO2. The composition is shown in molar terms in this diagram to easily depict the area of ​​the expected flammable ternary composition (shaded).

[0051] The upper curve, starting from the CO2 peak, shows the gas phase composition of the leak, and the lower curve, also starting from the CO2 peak, shows the liquid phase composition of the leak. The leak begins in the lower right corner of the triangle near the CO2 peak.

[0052] It is clear that both phase compositions are well outside the flammable region at all points in the leakage event. Therefore, this mixture is classified as non-flammable under fractionation.

[0053] Example 5 The performance of compositions containing 86% CO2, 7% R-32, and 7% R-134a was investigated using the air conditioning cycle model previously described in Example 1. The results are shown in Table 5. [Table 5]

[0054] Example 6 Next, the performance of selected ternary compositions containing CO2, R-32, and R-1132a was investigated using the following transitional criticality air conditioning cycle model. [Table 6]

[0055] The results are shown in Tables 6 and 7 below. [Table 7] [Table 8]

[0056] As you can see, adding R-1132a slightly reduces energy efficiency and cooling capacity, but improves compressor discharge temperature and reduces evaporator temperature glide.

[0057] The effects of R-1132a and R-32 content on the selected performance parameters are further shown in Figures 16 and 17.

[0058] Figure 16 shows the effect of R-1132a and R-32 content on the coefficient of cooling performance (COP).

[0059] Figure 17 shows the effect of R-1132a and R-32 content on volumetric cooling capacity.

[0060] The term "binary" used in Figures 16 and 17 refers to the binary composition of R-32 and CO2 (R-1132a does not exist).

[0061] The present invention encompasses the following aspects. [Aspect 1] A refrigerant composition comprising carbon dioxide (CO2, R-744) and 1 to 32% by weight of difluoromethane (R-32) based on the total weight of the refrigerant composition. [Aspect 2] The refrigerant composition according to embodiment 1, wherein the difluoromethane is present in an amount of 1 to 25% by weight based on the total weight of the refrigerant composition. [Aspect 3] The refrigerant composition according to embodiment 2, wherein the difluoromethane is present in an amount of 20 to 25% by weight based on the total weight of the refrigerant composition. [Aspect 4] The refrigerant composition according to embodiment 2 or 3, comprising less than 22% by weight of difluoromethane (R-32) based on the total weight of the refrigerant composition. [Aspect 5] The refrigerant composition according to embodiment 2 or 3, comprising less than 21% by weight of difluoromethane (R-32) based on the total weight of the refrigerant composition. [Aspect 6] The refrigerant composition according to embodiment 2, which is a binary refrigerant composition comprising 75-99% by weight of carbon dioxide and 25-1% by weight of difluoromethane. [Aspect 7] The refrigerant composition according to embodiment 2, which is a binary refrigerant composition comprising 75-80% by weight of carbon dioxide and 25-20% by weight of difluoromethane. [Aspect 8] The refrigerant composition according to embodiment 2, which is a binary refrigerant composition comprising 78% by weight of carbon dioxide ±1% by weight and 22% by weight of difluoromethane ±1% by weight. [Aspect 9] The refrigerant composition according to embodiment 2, which is a binary refrigerant composition comprising 79% by weight of carbon dioxide ±1% by weight and 21% by weight of difluoromethane ±1% by weight. [Aspect 10] A refrigerant composition according to any one of embodiments 2 to 5, further comprising 1,1,1,2-tetrafluoroethane. [Aspect 11] A refrigerant composition according to any one of embodiments 2 to 5 and 10, further comprising a tetrafluoropropene, preferably selected from 2,3,3,3-tetrafluoropropene (R-1234yf) and 1,3,3,3-tetrafluoropropene (R-1234ze(E)). [Aspect 12] The refrigerant composition according to embodiment 10, further comprising 2,3,3,3-tetrafluoropropene (R-1234yf) or 1,3,3,3-tetrafluoropropene (R-1234ze(E)), wherein the amounts of 1,1,1,2-tetrafluoroethane and the selected tetrafluoropropene compound are such that a binary mixture of either R-1234yf or R-1234ze(E)e and R-134a is nonflammable. [Aspect 13] The refrigerant composition according to embodiment 10, which is a ternary refrigerant composition comprising 86% by weight of carbon dioxide ±1% by weight, 7% by weight of difluoromethane ±1% by weight, and 7% by weight of 1,1,1,2-tetrafluoroethane ±1% by weight. [Aspect 14] A refrigerant composition according to any one of embodiments 2 to 5, 10, or 11, further comprising 1,1-zilfluoroethylene (R-1132a). [Aspect 15] The refrigerant composition according to embodiment 14, wherein, based on the total weight of the refrigerant composition, R-1132a is present in an amount of up to 20 or 22% by weight, for example 2 to 15% by weight, preferably 3 to 14% by weight, for example 3 to 12% by weight. [Aspect 16] The refrigerant composition according to embodiment 14 or 15, wherein the refrigerant composition is a ternary composition comprising 50 to 95% by weight of carbon dioxide, 1 to 32% by weight of difluoromethane, and 1 to 20% by weight of R-1132a, based on the total weight of the refrigerant composition. [Aspect 17] The refrigerant composition according to embodiment 16, comprising, based on the total weight of the refrigerant composition, 55 to 93% by weight of carbon dioxide, 2 to 32% by weight of difluoromethane, and 2 to 15% by weight of R-1132a, for example, 64 to 93% by weight of carbon dioxide, 2 to 25% by weight of difluoromethane, and 2 to 14% by weight of R-1132a, for example, 65 to 93% by weight of carbon dioxide, 2 to 22% by weight of difluoromethane, and 2 to 14% by weight of R-1132a. [Aspect 18] A composition according to any one of embodiments 10, 14, or 15, comprising carbon dioxide, difluoromethane, R-1132a, and 1,1,1,2-tetrafluoroethane. [Aspect 19] A refrigerant composition according to any one of embodiments 1 to 18, which is non-flammable. [Aspect 20] A refrigerant composition according to any one of embodiments 1 to 19, having a global warming potential of less than 300, preferably less than 150. [Aspect 21] A transcritical heat transfer system for providing heating and / or cooling, comprising a refrigerant composition according to any one of embodiments 1 to 20. [Aspect 22] A refrigeration, air conditioning, or heat pump system comprising a refrigerant composition according to any one of embodiments 1 to 20. [Aspect 23] A transitional critical heat transfer system according to embodiment 21, which is an automotive air conditioning system. [Aspect 24] A transitional critical heat transfer system according to embodiment 21, which is an automotive heat pump system. [Pattern 25] A transcritical heat transfer system according to embodiment 21, which provides both heating and air conditioning for automotive applications. [Aspect 26] A transitional critical heat transfer system according to embodiment 21, which is a heat pump system for generating hot water. [Aspect 27] A transitional critical heat transfer system according to embodiment 21, which is a refrigeration system for a supermarket. [Aspect 28] A transitional critical heat transfer system according to embodiment 21, which is a residential air conditioning system. [Aspect 29] A transitional critical heat transfer system according to embodiment 21, which is a refrigerated transport system. [Aspect 30] A transcritical heat transfer system according to any one of embodiments 21 and 23-29, further comprising a lubricant, preferably a polyol ester or polyalkylene glycol lubricant. [Aspect 31] The refrigeration, air conditioning, or heat pump system according to embodiment 22, further comprising a lubricant, preferably a polyol ester or polyalkylene glycol lubricant. [Aspect 32] A transcritical heat transfer system according to any one of embodiments 21 and 23-29, which uses a single-stage compression cycle. [Aspect 33] A transcritical heat transfer system according to any one of embodiments 21 and 23-29, which uses a two-stage compression cycle. [Aspect 34] An electric vehicle equipped with a transitional criticality air conditioning and / or heat pump system as described in any one of embodiments 22 to 25. [Aspect 35] A method for generating cooling, comprising evaporating a refrigerant composition according to any one of embodiments 1 to 20 in the vicinity of a body to be cooled. [Aspect 36] A method for generating heat, comprising condensing a refrigerant composition according to any one of embodiments 1 to 20 in the vicinity of an object to be heated. [Brief explanation of the drawing]

[0062] [Figure 1] This shows the transitional criticality cycle for modeling. [Figure 2]This shows the cooling COP of an R-32 / R-744 blend in air conditioning mode. [Figure 3] This shows the volumetric capacity of the R-32 / R-744 blend in air conditioning mode. [Figure 4] This shows the gas cooler pressure for the R-32 / R-744 blend in air conditioning mode. [Figure 5] This shows the evaporator temperature glide for R-32 / R-744 blends in air conditioning mode. [Figure 6] This shows the heating COP of an R-32 / R-744 blend in heat pump mode. [Figure 7] This shows the volumetric heating capacity of the R-32 / R-744 blend in heat pump mode. [Figure 8] This shows the gas cooler pressure for an R-32 / R-744 blend in heat pump mode. [Figure 9] This shows the evaporator temperature glide of an R-32 / R-744 blend in heat pump mode. [Figure 10] This shows a two-stage transcritical vapor compression cycle. [Figure 11] This shows the cooling COP of a two-stage cycle compared to the R-744. [Figure 12] This shows the gas cooler pressure in a two-stage cycle. [Figure 13] This shows the evaporator temperature glide in a two-stage cycle. [Figure 14] This shows the displacement during the second stage cycle of the first stage compressor. [Figure 15] This shows the separation pathways for ternary CO2 / R-32 / R-134a (86% / 7% / 7%) at -40℃. [Figure 16] The COP of the CO2 / R-32 / R-1132a blend is shown. [Figure 17] This shows the volumetric cooling capacity of the CO2 / R-32 / R-1132a blend.

Claims

1. Based on the total weight of the refrigerant composition, 50 to 95% by weight of carbon dioxide (CO2) ２ , R-744) and, Based on the total weight of the refrigerant composition, 1 to 25% by weight of difluoromethane (R-32) and Based on the total weight of the refrigerant composition, 2 to 15% by weight of 1,1-difluoroethylene (R-1132a) and A tetrafluoropropene selected from 2,3,3,3-tetrafluoropropene (R-1234yf) and 1,3,3,3-tetrafluoropropene (R-1234ze(E)), A refrigerant composition containing the following:

2. The refrigerant composition according to claim 1, comprising 1% by weight or more and less than 22% by weight of difluoromethane (R-32) based on the total weight of the refrigerant composition.

3. The refrigerant composition according to claim 1 or 2, wherein R-1132a is present in an amount of 3 to 14% by weight based on the total weight of the refrigerant composition.

4. The refrigerant composition according to claim 3, wherein R-1132a is present in an amount of 3 to 12% by weight based on the total weight of the refrigerant composition.

5. A refrigerant composition according to any one of claims 1 to 4, which is non-flammable.

6. A refrigerant composition according to any one of claims 1 to 5, comprising less than 0.5% by weight of any further (hydro)(fluoro) compound.

7. A refrigerant composition according to any one of claims 1 to 6, having a global warming potential of less than 300.

8. The refrigerant composition according to claim 7, having a global warming potential of less than 150.

9. A transitional critical heat transfer system for providing heating and / or cooling, comprising a refrigerant composition according to any one of claims 1 to 8.

10. A refrigeration, air conditioning, or heat pump system comprising the refrigerant composition according to any one of claims 1 to 8.

11. The transitional critical heat transfer system according to claim 9, which is an automotive air conditioning system and / or an automotive heat pump system.

12. The transitional critical heat transfer system according to claim 9, which is a heat pump system for generating hot water, or a refrigeration system for a supermarket, or a residential air conditioning system, or a refrigerated transport system.

13. The transitional heat transfer system according to claim 9, 11, or 12, further comprising a lubricant.

14. The transitional heat transfer system according to claim 13, wherein the lubricant further comprises a polyol ester or a polyalkylene glycol lubricant.

15. The refrigeration, air conditioning, or heat pump system according to claim 10, further comprising a lubricant.

16. The refrigeration, air conditioning, or heat pump system according to claim 15, wherein the lubricant further comprises a polyol ester or a polyalkylene glycol lubricant.

17. A transcritical heat transfer system according to claim 9, 11, or 12, using a single-stage compression cycle.

18. A transcritical heat transfer system according to claim 9, 11, or 12, using a two-stage compression cycle.

19. An electric vehicle equipped with the transitional critical heat transfer system described in claim 11.

20. A method for generating cooling, comprising evaporating a refrigerant composition according to any one of claims 1 to 8 in the vicinity of a body to be cooled.

21. A method for generating heat, comprising condensing a refrigerant composition according to any one of claims 1 to 8 in the vicinity of an object to be heated.

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