LOW GWP REFRIGERANT MIXTURES

Description

[0001] This invention relates to refrigerant compositions which can be used in thermal pumps to pump heat from a lower temperature to a higher temperature by the input of work. When such devices are used to generate lower temperatures, they are typically called refrigerators or air conditioners. Where they are used to produce higher temperatures, they are typically termed heat pumps. The same device may supply heating or cooling depending upon the user's requirement. This type of thermal pump may be called a reversible heat pump or reversible air conditioner.

[0002] Chlorofluorocarbons (CFCs) such as CFC-12 and R502 and hydrochlorofluorocarbons (HCFCs) such as HCFC-22 have been widely used as refrigerants, but migrate to the stratosphere where they are broken down by ultra violet light producing chlorine atoms that destroy the ozone layer. These Ozone Depleting Substances (ODS) are being replaced by non-ozone depleting alternatives such as hydrofluorocarbons (HFCs), which are non-flammable, efficient and of low toxicity. In certain applications, particularly but not specifically related to low temperature refrigeration systems often used in supermarkets, R502 was the main refrigerant of choice due largely to its lower discharge temperature compared to R22. As a consequence of the global environmental agreement to protect the Ozone Layer embodied in the Montreal Protocol, R502 was banned and was largely replaced by the HFC blends R404A and R507. However, R404A and R507, while being excellent refrigerants in terms of energy efficiency, non-flammability, low toxicity and thermodynamic properties, nevertheless have Global Warming Potentials (GWP)s which are at the high end of the commonly used HFCs.

[0003] In this specification the numerical value for a Global Warming Potential (GWP) refer to an Integrated Time Horizon (ITH) of 100 years as contained in the Inter-Governmental Panel on Climate Change Fourth Assessment Report (AR4).

[0004] Although R22, which has been widely used in air conditioning systems, has a much lower ability to destroy ozone compared to CFCs, it is being phased out under the Montreal Protocol. Non-ozone depleting R410A has proved an excellent replacement for R22 in new air conditioning equipment, including split systems, but it is also now being phased down because the comparatively high GWP (2088) means it is no longer environmentally acceptable.

[0005] The EU and other territories have imposed GWP quotas and / or taxes to progressively reduce the availability of R404A, R507 and R410A. These actions have two key consequences. Firstly, there will be shortages of these refrigerants available to service existing equipment and charge new equipment which will disrupt the refrigeration and air conditioning industries. Secondly, the price of remaining refrigerant will rapidly increase as supply can no longer meet demand. Without replacement refrigerants, critical equipment, e.g. for preserving food in supermarkets and air conditioning in hospitals, may stop functioning with serious social repercussions.

[0006] The composition of R404A is: R12544%;R143a52%; andR134a4%(GWP = 3922)

[0007] The composition of R507 is: R12550%; andR143a50%(GWP = 3985)

[0008] The composition of R410A is: R12550%; andR3250%(GWP = 2088)

[0009] WO2017 / 151488 discloses refrigerant compositions comprising HFC-32, HFC-125, HFO-1234yf, HFC-134a and CO 2.

[0010] WO2016 / 156812 discloses a composition comprising R125 20-35%, R32 20-35%, R1234ze(E) 25-50% and R227ea 1-10% .

[0011] According to a first aspect of the present invention there is provided a refrigeration composition consisting essentially of: carbon dioxide1-35% an HFO selected from the group consisting of: R1234yf and R1234ze(E) and mixtures thereof30-92%R321-30%R1251-30%R227ea1-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0012] In this specification percentages or other amounts are by mass unless indicated otherwise. Amounts are selected from any ranges given to total 100%.

[0013] The term "consisting of" is used in this specification to refer to compositions which include only the recited ingredients, disregarding trace amounts of any impurities.

[0014] The term "consisting essentially of" is used in this specification to refer to compositions which consist of the recited ingredients with the possible addition of minor amounts of any further ingredients which do not substantially alter the essential refrigerant properties of the composition. These compositions include compositions which consist of the recited ingredients. Compositions which consist of the recited ingredients may be particularly advantageous.

[0015] This invention relates to low GWP blends, which particularly, but not exclusively, are compositions that can replace R404A, R507 and R410A in existing, modified or new refrigeration and air conditioning systems. The continued operation of existing and modified systems is facilitated. The blends have zero Ozone Depletion Potentials, so that they have no adverse effect on stratospheric ozone. The invention also provides compositions which may continue to be used in the event of progressive tightening of GWP restrictions, while minimising the cost to the user.

[0016] This invention relates particularly to refrigerant compositions that have GWP values in the range 0.5 to 1050. The values in this range are significantly lower than those of R404A, R507 and R410A. Exemplary compositions may have ASHRAE safety classifications of A1 (low toxicity / non-flammable) or A2L (low toxicity / slightly flammable). The compositions may possess energy efficiencies and cooling capacities at least comparable to the fluids they are replacing. The compositions may have maximum operating pressures no greater than 3 bar preferably 2 bar greater at 45°C than the refrigerants they may replace. Compositions with relatively high GWPs tend to be non-flammable (A1) while compositions with lower GWPs tend to be slightly flammable (A2L). For existing equipment there may be little scope for carrying out physical modifications. Therefore, non-flammability (A1) is essential for use in existing equipment. Compositions with higher GWP values may be required. For existing equipment, where modifications are possible and especially for new installations designed to exploit their advantageous properties, then blends with lower GWPs are preferred, even if they have an A2L rating.

[0017] The term "glide" has been previously defined as the temperature difference between the bubble point and the dew point at the specified constant pressure. This may be referred to as the 'intrinsic' refrigerant glide. Defined in this way, "glide" is a purely thermodynamic property of a refrigerant and is independent of equipment and operating conditions.

[0018] In the condenser where the refrigerant moves from the dew point to the bubble point as it condenses, the observed glide is a combination of the intrinsic glide of the refrigerant plus the glide induced by the pressure drop necessary to maintain the refrigerant flow.

[0019] In an evaporator where a portion of the refrigerant has already vaporised in the expansion device for example a valve or capillary tube, a two phase mixture enters the evaporator. In this case the glide is the difference between the entry temperature and the dew point. This difference may depend on operating conditions. The observed glide will be the intrinsic glide of the refrigerant minus the glide caused by the pressure drop in the evaporator required to maintain the refrigerant flow. A measured or calculated evaporator glide under specified conditions may be used.

[0020] In this specification temperature glides under the specified operating conditions for the equipment may be classified as follows: 1.Negligible glide-less than 0.5K2.Small glide-0.5K to 2.0K3.Medium glide-more than 2.0K to 5.0K4.Wide glide-more than 5K to 10.0K5.Very wide glide-more than 10.0K

[0021] Compositions of the present invention may have a wide or very wide temperature glide.

[0022] Exemplary compositions may consist essentially of CO 2 , an HFO with a normal boiling point less than -15°C, and one or more of R32, R227ea, R134a and R125. Exemplary HFOs are R1234yf and R1234ze(E). These fluids may provide a combination of appropriate vapour pressures for formulating R404A, R507 and R410A replacements with low flammability and low toxicity. They may provide compositions where the flammability of the HFOs and R32 can be partially or completely compensated for, by the presence of the non-flammable gases CO 2 , R125 and R227ea. Furthermore, the relatively high GWPs of R125 and R227ea and the moderate GWP of R32 can be offset by the very low GWPs of CO 2 and the HFOs.

[0023] Exemplary embodiments of this invention provide refrigerant compositions that allow equipment to continue operating at pressures suitable for use with R404A, R507 or R410A. These embodiments provide replacement refrigerants for servicing existing equipment and charging new equipment. This object may be achieved with compositions having GWPs not exceeding 1050. Initially, a reduced EU GWP quota may provide adequate latitude for compositions in accordance with this invention having thermodynamic and flammability properties that enable them to be retrofitted into existing designs of R404A, R507 and R410A equipment with few or no modifications. This is advantageous because a retrofit composition minimises the cost to the equipment owner.

[0024] As GWP regulations further reduce the supply, it may become difficult to provide sufficient refrigerant to meet market demands using retrofit compositions. Surprisingly, we have found that compositions with GWPs of less than 800, which, in themselves, do not have the thermodynamic properties to be retrofit fluids, can be used, for example, at the annual service, to top up the refrigerant remaining in a unit containing R404A, R507 or R410A, thus enabling the equipment to continue operating, for example, for at least 5 years, despite small persistent leakage. Such compositions may be termed "extenders". A further aspect of this invention is to provide an extender with GWP of less than 300, which may be used as a refrigerant to service existing equipment as GWP regulations become stricter. These compositions may enable the continued use of existing technology and equipment, thereby avoiding the high cost of replacing equipment that is still functioning or the cost of developing new technologies.

[0025] While hydrocarbons, ammonia and carbon dioxide (CO 2 ) are technically feasible refrigerants for refrigeration and air conditioning systems and have considerably lower GWPs than HFCs, they are not direct replacements for R507 and R410A, since they have inherent disadvantages which work against their general usage, particularly in public areas such as supermarkets. Highly flammable hydrocarbons can only be used safely in conjunction with a secondary refrigeration circuit, which reduces energy efficiency and increases costs, or with small charges, in turn severely limiting the maximum cooling duty for which they can be used. Even when such safety precautions have been taken, hydrocarbon refrigerants and ammonia have caused building damage, injury and death. CO 2 must be used in the transcritical state on the high-pressure side of the system to allow heat rejection to ambient air. Pressures are often in excess of 100 bar, again resulting in an energy penalty and also a significantly higher capital cost compared to conventional R404A, R507 and R410A systems. Ammonia is markedly toxic. Leaks from industrial refrigeration installations may cause death and injury. Because of these adverse properties, hydrocarbons, ammonia and CO 2 cannot be retrofitted into existing R404A, R507 or R410A units.

[0026] Exemplary compositions have direct GWP values which are less than about 1050. GWP values are widely recorded in the literature for example as published by the US Environmental Protection Agency (EPA) or IPCC Reports.

[0027] Advantageous embodiments of this invention consist essentially of blends of carbon dioxide and R1234ze(E) and / or R1234yf, R125, R134a R227ea and R32, in the presently claimed proportions, wherein the compositions have safety classifications of A1 or A2L, according to ASHRAE Standard 34, while providing similar or superior refrigerating effects and performances as the refrigerants they are intended to replace, but with maximum operating pressures that allow them to be used with equipment components pressured rated for R404A, R507 or R410A.

[0028] Compositions of this invention may be used to completely or partially replace a refrigerant, for example, R404A, R410A or R507. The compositions may be used for completely retrofitting existing equipment or for topping up existing equipment, for example, following a gradual leak. Alternatively, the compositions may be used as refrigerants in new or original (OEM) equipment.

[0029] In a first exemplary embodiment the composition may be used in air conditioning equipment operating at an evaporating temperature in the range of about 0°C to about 15°C, for example, from about 2°C to about 15°C, for example, the equipment designed for use with R410A.

[0030] In a second exemplary embodiment, the composition may be used in low temperature refrigeration equipment operating at an evaporating temperature, for example, from about - 15°C to about -20°C, for example, with equipment designed for use with R404A or R507.

[0031] Exemplary compositions of this invention are capable of retaining the properties of the existing refrigerant, when used in combination with the existing refrigerant or as a complete replacement for the existing refrigerant. The following properties may be achieved.

[0032] The GWP of the refrigerant should be lower than the GWP of the original refrigerant.

[0033] The cooling capacity of the refrigerant should be similar, for example, (±20%) to that of the original refrigerant. This is important to enable the equipment to function adequately in a hot environment.

[0034] The discharge pressure should not exceed the maximum pressure rating of the equipment.

[0035] The discharge temperature should not significantly exceed the discharge temperature that the equipment is designed for. If the discharge temperature is excessive then the working life of the equipment may be reduced.

[0036] It is an advantage that the compositions in accordance with this invention may have discharge temperatures which are lower than may be expected following a standard calculation, for example, using the Nist Cycle D method. Exemplary compositions may have discharge temperatures which are lower than the calculated values and for example about 5°C to 10°C above the measured values for R404A, R507 or R410A.

[0037] The power consumption of the equipment when using the replacement refrigerant should not be significantly higher, for example, not more than 20% higher in comparison to the power consumption when using the original refrigerant.

[0038] Exemplary compositions may have the further advantage that they are not azeotropes or azeotrope-like. Preferred compositions boil over a temperature range greater than about 10°C, for example, greater than 20°C.

[0039] It is a common belief that an azeotrope-like composition is necessary. The present inventors have unexpectedly discovered that azeotrope-like compositions are not necessary and may even be disadvantageous. This discovery is particularly useful when using a direct heat exchange (DX) exchanger in which a progressive increase in temperature is dependent on the glide of the refrigerant.

[0040] In condenser equipment using a refrigerant composition, in this invention, the pressure drop glide is in the same direction as the refrigerant glide so that the effects are additive.

[0041] In contrast, in an evaporator, the pressure drop glide is in the opposite direction to the refrigerant glide so that the two effects may partially, or completely, cancel out. An evaporator cools, for example, an air stream or a liquid stream over a range from a higher temperature to a lower temperature. If the temperature glide of the evaporating refrigerant is significantly greater than the required cooling range, then the efficiency on the unit may be compromised. Preferably glide should be equal to, or less than, the range. Pressure-induced evaporator glide may act in opposition to the intrinsic refrigerant glide to produce an observed glide that is acceptable for a required cooling range.

[0042] In the event that the availability of high GWP R404A, R507 and R410A may be constrained by the EU F-Gas regulations, and similar global legislation following the ratification of the Kigali Amendment to the Montreal Protocol, insufficient quantities of these refrigerants may be available to service existing equipment. Major modifications of existing R404A, R507 and R410A equipment may be prohibitively expensive. The EU is limiting availability by further reducing GWP quotas to suppliers from 2018. Exemplary embodiments of this invention may overcome the quota limitation by providing refrigerants comprising an HFO, CO 2 and R227ea that can be used to "top up" R404A, R507 and R410A units, allowing them to operate for at least a further five years. Typically, commercial refrigeration equipment loses 5 to 20% of its refrigerant charge each year and is topped up with new refrigerant at its annual service. Surprisingly, we have found that blends comprising carbon dioxide, R1234yf and / or R1234ze(E), R227ea, R32, R125 and, optionally R134a, may be added to the R404A, R507 or R410A, remaining in a thermal pump after a leak, to allow continued operation of the device. Such compositions are called "extenders", i.e. they extend the working life of the units to which they are added. Because most existing installations are not designed to handle flammable (A2) refrigerants, extenders are non-flammable A1 refrigerants. To ensure effective operation, the compositions require suction capacities and maximum operating temperatures comparable to the refrigerants they are replacing. Preferably, the GWPs of extender compositions should be less than 800 and preferably less than 300, to maximise the quantity of refrigerants available for topping up within the constraints of government-imposed quotas.

[0043] According to a third aspect of this invention, there is provided a refrigerant extender composition in accordance with the first aspect of this invention.

[0044] R227ea has a relatively high GWP of 3220 but is non-flammable and tends to co-distil with R1234ze(E) and R1234yf, thus helping the formulation of non-flammable blends. Conversely, R32 has a lower GWP (675), but is flammable. Since non-flammable extender blends are required, then it may be advantageous to omit R32 to maximise the quantity of R227ea that can be added to ensure non-flammability. For blends with a GWP not exceeding a GWP of 800, then the maximum R227ea content may be about -24.8%; for a GWP not exceeding 500, the maximum amount of R227ea may be about 15.5%; and for a GWP not exceeding 300, the maximum may be about 9.2%.

[0045] In embodiments the amount of R227ea may be in the range of 4% to 15%.

[0046] Generally, refrigerant leaks may be small (5 to 20% per annum) allowing topping up at an annual service. However, catastrophic refrigerant losses may occur when most of the charge is lost, essentially requiring a complete replacement of the original refrigerant. The compositions described above, as extenders, may be used for this purpose, if necessary, by modifying the units to enable them to be compatible with the specific physical properties of these blends. But the compositions may result in excessive discharge temperatures in the condensers and evaporators if systems cannot be modified. In these circumstances, compositions are preferred that have inherently acceptable discharge temperatures, suction specific volumes, an A1 safety rating and maximum operating pressures to allow them to be used in existing R404A, R507 or R410A equipment. Surprisingly, we have found that this preferred combination of properties can be achieved by compositions comprising R32, R125, R1234yf, R1234ze and R227ea, as claimed in this invention.

[0047] The present invention may enable the replacement of R404A, R507 and R410A - the most commonly used refrigerants in refrigeration and air conditioning equipment - providing a substantial reduction in GWP exceeding 80%, with blends having a GWP between 1 and 800 without any reduction in performance, including energy efficiency and capacity.

[0048] An exemplary refrigerant composition may consist essentially of the following: carbon dioxide5-20%an HFO selected from the group consisting of: R1234yf and R1234ze(E) and mixtures thereof30-92%R325-30%R1255-30%R227ea4-15%R134a0-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0049] An exemplary refrigerant composition which may be used to completely or partially replace R404A, R507 or R410A consists or consists essentially of: R1256-23%carbon dioxide6-20%R1234ze55-68%R227ea6-15%R326-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0050] An exemplary refrigerant composition which may be used to completely, or partially, replace R404A, R507 or R410A, consists or consists essentially of: R1256-20%carbon dioxide6-18%R1234ze55-67%R227ea7-15%R327-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100% .

[0051] An exemplary refrigerant composition may consist essentially of the following: R1259.5%carbon dioxide8%R1234ze65%R227ea8%R329.5% wherein the percentages are by mass.

[0052] An exemplary refrigerant composition may consist or consist essentially of one of the following: (a) R1259.5%carbon dioxide9%R1234ze58%R227ea7%R329.5%R134a7% wherein the percentages are by mass. (b) R12511%carbon dioxide11%R1234ze57%R227ea7%R3211%R134a3% wherein the percentages are by mass. (c) R12518%carbon dioxide11%R1234ze44%R227ea6%R3217%R134a4% wherein the percentages are by mass. (d) \R12511%carbon dioxide11%R1234ze55%R227ea7%R3211%R134a5% wherein the percentages are by mass. (e) R12513%carbon dioxide11%R1234ze53%R227ea7%R3213%R134a3% wherein the percentages are by mass. (f) R12513%carbon dioxide11%R1234ze55%R227ea7%R3213%R134a1% wherein the percentages are by mass. (g) R12514%carbon dioxide11%R1234ze51%R227ea7%R3214%R134a3% wherein the percentages are by mass. (h) R12514%carbon dioxide11%R1234ze55%R227ea7%R3213%R134a- wherein the percentages are by mass. (i) R12510.5%carbon dioxide11%R1234ze57%R227ea7%R3210.5%R134a4% wherein the percentages are by mass. (j) R12510.5%carbon dioxide11%R1234ze58%R227ea7%R3210.5%R134a3% wherein the percentages are by mass. (k) R12511.5%carbon dioxide10%R1234ze57%R227ea7%R134a3%R3211.5% (l) R12511.5%carbon dioxide10%R1234ze56%R227ea8%R3211.5%R134a3%

[0053] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A, R507 or R410A, may consist or consist essentially of one of the following: (a) R12519%carbon dioxide10%R1234ze44%R227ea3%R3217%R134a7% wherein the percentages are by mass. (b) R12518%carbon dioxide11%R1234ze44%R227ea7%R3211%R134a3% wherein the percentages are by mass.

[0054] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A, R507 or R410A, may consist or consist essentially of: R1251-30%carbon dioxide1-30%R1234yf35-70%R227ea1-10%R321-30%R134a0-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0055] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1255-30%carbon dioxide5-25%R1234yf50-70%R227ea2-10%R325-30% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0056] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1256-27%carbon dioxide6-20%R1234yf55-70%R227ea3-10%R326-27% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0057] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1257-25%carbon dioxide7-20%R1234yf58-69%R227ea5-10%R327-25% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0058] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1257-23%carbon dioxide7-20%R1234yf58-68%R227ea6-10%R327-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0059] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1257-20%carbon dioxide7-18%R1234yf59-67%R227ea7-10%R327-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0060] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1259.5%carbon dioxide8%R1234yf65%R227ea8%R329.5% wherein the percentages are by mass.

[0061] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist or consist essentially of: R1259-25%carbon dioxide7-20%R1234yf35-60%R227ea2-10%R329-25% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0062] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist or consist essentially of: R12512-23%carbon dioxide8-20%R1234yf35-55%R227ea3-10%R3212-23% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0063] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist or consist essentially of: R12519%carbon dioxide16%R1234yf41%R227ea5%R3219% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0064] An exemplary refrigerant composition, which may be used to provide an extender or new equipment alternative for R404A, R507 or R410A, may consist or consist essentially of: carbon dioxide1-35%an HFO selected from the group consisting of R1234yf and HFO1234ze(E) or mixtures thereof,30-95%R321-30%R1251-30%and R227ea1-15% and mixtures thereof, wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0065] An exemplary refrigerant composition not presently claimed, which may be used to provide an extender or new equipment alternative for R404A, R507 or R410A. may consist or consist essentially of: carbon dioxide10-30%an HFO selected from R1234yf or R1234ze(E) or mixtures thereof45-85%R227ea5-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0066] An exemplary refrigerant composition, not presently claimed which may be used to provide an extender or new equipment alternative for R404A, R507 or R410A. may consist or consist essentially of: carbon dioxide10-25%an HFO selected from R1234yf or R1234ze(E) and mixtures thereof60-83%R227ea5-12% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0067] An exemplary refrigerant composition, not presently claimed which may be used to provide an extender or new equipment alternative for R404A or R507, may consist or consist essentially of:carbon dioxide22%R227ea9%and R1234ze(E) or R1234yf69% wherein the percentages are by mass.

[0068] An exemplary refrigerant composition, not presently claimed which may be used to provide an extender or new equipment alternative for R410A, may consist or consist essentially of: carbon dioxide21-30%R1234ze(E)60-71%R227ea7-10% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0069] An exemplary refrigerant composition, not presently claimed which may be used to provide an extender or new equipment alternative for R410A, may consist or consist essentially of: carbon dioxide25%R227ea9%and R1234ze(E) or R1234yf66% wherein the percentages are by mass.

[0070] An exemplary refrigerant composition, not presently claimed which may be suitable as a replacement for R404A or R507 in refrigeration equipment, may consist or consist essentially of: carbon dioxide10-20%and an HFO selected from R1234yf and R1234ze(E) or mixtures thereof90-80% wherein the percentages are by mass and are selected from the ranges quoted to total 100%

[0071] An exemplary refrigerant composition, not presently claimed which is suitable as a replacement for R404A or R507 in refrigeration equipment, may consist or consist essentially of: carbon dioxide10-30%R1234ze70-90% wherein the percentages are by mass.

[0072] An exemplary refrigerant composition, not presently claimed which is suitable as a replacement for R404A or R507 in refrigeration equipment, may consist or consist essentially of: carbon dioxide15-25%R1234ze75-90% wherein the percentages are by mass

[0073] An exemplary refrigerant composition, not presently claimed which is suitable as a replacement for R404A or R507 in refrigeration equipment, may consist or consist essentially of: carbon dioxide15%R1234ze85% wherein the percentages are by mass

[0074] An exemplary refrigerant composition, not presently claimed which is suitable as a replacement for R404A or R507 in refrigeration equipment, may consist or consist essentially of: carbon dioxide20%R1234ze80% wherein the percentages are by mass

[0075] An exemplary refrigerant composition, not presently claimed which is suitable as a replacement for R404A or R507 in refrigeration equipment, may consist or consist essentially of: carbon dioxide12-23%R1234yf77-88% wherein the percentages are by mass.

[0076] An exemplary refrigerant composition, not presently claimed which is suitable as a replacement for R410A in air conditioning equipment, may consist or consist essentially of: carbon dioxide12-20%and an HFO selected from R1234yf and R1234ze(E) or mixtures thereof80-88% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0077] An exemplary refrigerant composition, not presently claimed, which is suitable as a replacement for R410A in air conditioning equipment, may consist or consist essentially of: carbon dioxide15-23%R1234yf77-85% wherein the percentages are by mass.

[0078] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1256-23%carbon dioxide6-20%R1234ze55-68%R227ea6-15%R326-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0079] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1256-20%carbon dioxide6-18%R1234ze55-67%R227ea7-15%R327-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0080] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R12514%carbon dioxide11%R1234ze55%R227ea7%R3213% wherein the percentages are by mass.

[0081] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1259.5%carbon dioxide8%R1234ze65%R227ea8%R329.5% wherein the percentages are by mass.

[0082] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1259.5%carbon dioxide9%R1234ze57%R227ea15%R329.5% wherein the percentages are by mass.

[0083] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist or consist essentially of: R1259.5%carbon dioxide9%R1234ze58%R227ea14%R329.5% wherein the percentages are by mass.

[0084] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist or consist essentially of: R12512-23%carbon dioxide8-20%R1234ze35-55%R227ea3-10%R3212-23% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0085] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist or consist essentially of: R12519%carbon dioxide16%R1234ze41%R227ea5%R3219% wherein the percentages are by mass.

[0086] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A, R507 or R410A, may consist or consist essentially of: carbon dioxide1-35%R1234yf15-45%R1234ze15-50% and optionally, R32, R125 and R227ea or mixtures thereof, wherein the percentages of the components, including any optional components, are by mass, and are selected from the ranges quoted to total 100%.

[0087] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A, R507 and R410A, may consist or consist essentially of: R12519%carbon dioxide16%R1234ze20%R1234yf21%R227ea5%R3219% wherein the percentages are by mass.

[0088] An exemplary refrigerant composition may consist or consist essentially of: carbon dioxide1-35%an HFO selected from R1234yf and HFO1234ze(E) or mixtures thereof,30-95% and optionally, R32, R125, R134a and R227ea or mixtures thereof, wherein the percentages of the components, are by mass, and are selected from the ranges quoted to total 100%.

[0089] An exemplary refrigerant composition, not presently claimed, may consist essentially of: carbon dioxide1-35%an HFO selected from R1234yf and HFO1234ze(E) or mixtures thereof,30-95%and optionally, R321-30%R1251-30%R134a1-30%and R227ea1-15% or mixtures thereof, wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0090] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A, R507 or R410A, may consist essentially of: R1251-30%carbon dioxide1-30%R1234yf30-70%R134a2-30%R321-30%and optionally R227ea1-10% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0091] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12512-23%carbon dioxide8-20%R1234yf30-55%R134a7-25%R3212-23%and optionally R227ea3-10% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0092] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12518%carbon dioxide16%R1234yf31%R134a17%R3218% wherein the percentages are by mass and total 100%.

[0093] An exemplary refrigerant composition, not presently claimed, which may be used to provide an extender or new equipment alternative for R404A, R507 or R410A, may consist essentially of: carbon dioxide1-35%an HFO selected from R1234yf and R1234ze(E) or mixtures thereof,30-95%and optionally, R321-30%R1251-30%R134a1-30%and optionally R227ea1-10% or mixtures thereof, wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0094] An exemplary refrigerant composition, not presently claimed, which may be used to provide an extender or new equipment alternative for R404A, R507 or R410A, may consist essentially of: carbon dioxide10-30%an HFO selected from R1234yf or R1234ze(E) or mixtures thereof30-85%R134a3-25%and optionally R227ea5-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0095] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A, R507 or R410A, may consist essentially of: R1251-30%carbon dioxide1-30%R1234ze30-70%R134a1-30%R227ea1-15%R321-30% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0096] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist essentially of: R1255-30%carbon dioxide5-25%R1234ze30-68%R134a2-15%R227ea2-15%R325-30% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0097] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist essentially of: R12513%carbon dioxide11%R1234ze53%R227ea3%R134a7%R3213% wherein the percentages are by mass.

[0098] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist essentially of: R12514%carbon dioxide11%R1234ze51%R227ea3%R134a7%R3214% wherein the percentages are by mass.

[0099] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist essentially of: R1256-20%carbon dioxide6-18%R1234ze30-63%R134a5-10%R227ea7-15%R327-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0100] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist essentially of: R1259.5%carbon dioxide9%R1234ze58%R227ea7%R134a7%R329.5% wherein the percentages are by mass.

[0101] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist essentially of: R12510.5%carbon dioxide11%R1234ze57%R227ea7%R134a4%R3210.5% wherein the percentages are by mass.

[0102] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A and R507, may consist essentially of: R12510.5%carbon dioxide11%R1234ze58%R227ea7%R134a3%R3210.5% wherein the percentages are by mass.

[0103] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R1259-25%carbon dioxide6-20%R1234ze30-60%R134a2-30%R227ea2-10%R329-25% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0104] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12519%carbon dioxide10%R1234ze44%R134a7%R227ea3%R3217% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0105] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12518%carbon dioxide11%R1234ze44%R134a3%R227ea7%R3217% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0106] An exemplary refrigerant composition, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12518%carbon dioxide11%R1234ze44%R134a4%R227ea6%R3217% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0107] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12512-23%carbon dioxide8-20%R1234ze30-55%R134a5-25%R227ea3-10%R3212-23% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0108] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12512-23%carbon dioxide8-20%R1234ze30-55%R134a5-25%R3212-23% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0109] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12513-21%carbon dioxide10-18%R1234ze30-45%R134a8-20%R3213-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0110] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R410A, may consist essentially of: R12518%carbon dioxide16%HFO-1234ze31%R134a17%R3218% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

[0111] An exemplary refrigerant composition, not presently claimed, which may be used to provide a retrofit replacement, extender or new equipment alternative for R404A, R507 or R410A, may consist essentially of: carbon dioxide1-35%R1234yf15-45%HFO-1234ze15-50% and optionally, R32, R125, R134a and R227ea or mixtures thereof, wherein the percentages of the components, including any optional components, are by mass, and are selected from the ranges quoted to total 100%.

[0112] Although the above blends described as top-up blends for existing R404A, R507 and R410A units, they can also be used as compete replacements in some instances, if necessary by modifying the units to enable them to be compatible with the specific physical properties of these blends.

[0113] The present invention enables the replacement of R404A, R507 and R410A, the most commonly used refrigerants in refrigeration and air conditioning equipment, providing a substantial reduction in GWP exceeding 80% with blends having a GWP between 1 and 500, and without any reduction in performance including energy efficiency and capacity.

[0114] Each blend that is the subject of this invention may be used in a thermal pump lubricated by an oxygen containing oil, for example POE or PAG, or by such oils mixed with a hydrocarbon lubricant up to 50%, for example, a mineral oil, alkyl benzene or polyalpha olefin.

[0115] The invention is further described by means of examples but not in any limitative sense.Example 1

[0116] Refrigerant compositions shown in Table 1 were assessed as replacements for R410A both in existing and new equipment. Table 1Refrigerant #Chemical nameR410ABlend 1Blend 2R125pentafluoroethane5018.718R134a1,1,1,2-tetrafluoroethane07.44.2R744carbon dioxide010.310.9R1234vf2,3,3,3-tetrafluoroprop-1-ene000R227ea1,1,1,3,3,3 -hexafluoropropane035.8R1234ze(E)E-1,3,3,3-tetrafluoroprop-1-ene043.343.8R32difluoromethane5017.217.4GWP2088

[0117] A Toshiba reversible, split air conditioning unit, Model RAS-137SAV-E3, containing 0.8 kg R410A was used to cool a room and was monitored using temperature and pressure sensors positioned with a current meter to record the compressor electric power consumption. Data collected is shown in Table 2a. I(A) is the current in amps consumed by the compressor. T1 is the sensor located in the airstream leaving the evaporator.

[0118] T2 is the sensor located within in the room.

[0119] T3 is the sensor located in the airstream at the condenser outlet.

[0120] T4 is the sensor located in the airstream entering the condenser.

[0121] T5 is the sensor located on the refrigerant discharge from the compressor.

[0122] P1 is the suction pressure of the compressor. Table Refrigerant:2aR410AMode: CoolingT1(°C)T2(°C)T3(°C)T4(°C)T5(°C)P1(barg)I(A)Time(min)3128.227.126.345.714.390.18016.427.234.626.949.18.53.22514.526.43427.650.58.83.291012.825.935.228.749.88.53.351511.925.634.628.548.58.33.37201125.334.628.648.483.392510.525.134.428.848.77.93.3430

[0123] The R410A was replaced by 0.8 kg of Blend 1 with the composition shown in Table 1 and the device again run to cool the room. The data collected is shown in Table 2b. Table Refrigerant:2bBlend 1Mode: CoolingT1(°C)T2(°C)T3(°C)T4(°C)T5(°C)P1(barg)I(A)Time(min)27.727.928.626.527.611.85002026.929.127.341.53.664514.925.932.429.252.65.722.951013.925.531.628.853.75.722.91513.525.331.628.653.55.612.872013.125.232.328.953.45.552.92512.82532.129.353.25.462.983012.524.931.92953.15.412.9335

[0124] Blend 1 was then removed from the device which was then recharged with 0.8 kg of Blend 2. The device was again to cool the room and the data collected is shown in Table 2c. Table Refrigerant:2cBlend 2Mode CoolingT1(°C)T2(°C)T3(°C)T4(°C)T5(°C)P1(barg)I(A)Time(min)3029.831.329.639.213.580017.628.232.53055.25.64.4514.727.334.330.257.65.334.431013.826.934.630.657.55.154.421513.126.534.630.557.94.974.392012.326.234.530.858.14.864.3625122634.831.858.74.814.4330

[0125] The data shows that both Blend 1 and Blend 2 are effective retrofit replacements for R410 in a typical split air conditioning unit. Blend 1 is especially preferred because it has a lower current consumption and thus a lower power consumption than R410A. In other words, Blend 1 is more efficient than R410A.Example 2

[0126] Refrigerant compositions containing R1234ze(E) and R1234yf, shown in Table 2, were assessed as potential replacements for R410A in air conditioning units by modelling their performances using cycle simulations based on thermodynamic data generated by NIST's REFPROP v10. The results demonstrated that Blends 3 to 6 are acceptable replacements for R410A. Flow rates were similar so that the capillary expansion tubes, commonly found in smaller split air conditioning units, will continue to operate properly, thus avoiding costly modifications. The maximum operating pressures, which occurred in the condenser, were not more than 2 bar greater than that of R410A under comparable conditions, which is within the typical rating of a split air conditioning unit. The discharge temperatures were 15°C, or less, above that of R410A, avoiding thermal decomposition of lubricants or damage to other components. The GWPs of the blends were all less than 1000, so 1 tonne of a blend can replace more than 2 tonnes of R410A and remain within the EU imposed GWP cap. Table 3R410ABlend 3Blend 4Blend 5Blend 6R1250.519181717R134a0741014R744010111111R1234yf0002241R227ea03630R1234zeE04444220R320.5171717172088980998952912Input ParametersCooling dutykW11111CondenserMidpointC4551515150SubcoolkJ / kg55555External air temperatureC3535353535EvaporatorMidpointC715151515SuperheatC55555Compressor Isentropic efficiency0.70.70.70.70.7Electric motor efficiency0.90.90.90.90.9Volumetric efficiency0.90.90.90.90.9Output Results Condenser Pressurebara27.3026.3327.0228.3129.30Dew pointC45.0660.2960.7659.1957.11Bubble pointC44.9441.7141.2442.8142.89Mid pointC4551515150GlideK0.118.619.516.414.2Exit temperatureC39.936.736.237.837.9Heat outkW1.301.341.341.351.34Evaporator Pressurebara9.937.888.088.699.45Entry temperatureC6.961.460.972.403.38Dew pointC7.0416.5417.0315.6014.62Mid pointC79999GlideK0.115.116.113.211.2Exit temperatureC12.021.522.020.619.6Heat inkW11111Compressor Entry temperature to casingC12.021.522.020.619.6Entry temperature to compressorC25.738.338.936.634.5Discharge temperatureC82.496.597.394.290.6Compression ratio2.73.33.33.33.1Total power inputkW0.300.340.340.350.34Swept volumem^3 / h0.650.780.770.740.70System Suction specific volumekJ / m^349604135422443564622COP cooling3.322.952.942.892.95Mass flow ratekg / s0.006130.006220.006220.006550.00673 Example 3

[0127] Refrigerant composition Blend 7, shown in Table 4, was assessed as a replacement for R404A in the existing unit. Table 4Refrigerant #Chemical nameR404ABlend 7R125Pentafluoroethane4411.4R134a1,1,1,2-tetrafluoroethane43.3R143a1,1,1-trifluoroethane520R744carbon dioxide010.4R1234yf2,3,3,3-tetrafluoroprop-1-ene00R227ea1,1,1,3,3,3-hexafluoropropane07.4R1234ze(E)E-1,3,3,3-tetrafluoroprop-1-ene056.1R32Difluoromethane011.4GWP2088733

[0128] Testing a composition in an actual unit may take several days to assess its performance. Initial screening of candidates is therefore typically carried out by using a computer program to model the Rankine refrigeration cycle, using as input the thermodynamic properties of the composition and important operating parameters, to generate key performance criteria as output. This type of program is widely employed throughout the refrigeration industry. The performances of R404A and Blend 7 were modelled under similar conditions typical of a commercial refrigeration freezer cabinet, with a cycle model, using NIST's REFPROP v10 providing thermodynamic data. Since Blend 7 has very wide temperature glides in the evaporator and condenser, the midpoint temperatures of the glide ranges were selected to be representative of the evaporating and condensing temperatures. The input and output parameters are summarised in Table 5. Table 5Input R404ABlend 7Cooling dutykW11Condenser MidpointC3535SubcoolkJ / kg55Evaporator MidpointC-35-35SuperheatC1010Compressor Isentropic efficiency0.70.7Electric motor efficiency0.90.9Output CondenserPressurebara16.116.4Dew pointC35.247.5Bubble pointC34.822.5MidpointC3535GlideK0.425.1Exit temperatureC29.817.5Evaporator Pressurebara1.651.19Entry temperatureC-35.2-41.8Dew pointC-34.8-28.2MidpointC-35-35GlideK0.4913.5Exit temperatureC-24.8-18.2Heat inkW11Compressor Entry temperature to casingC-24.8-18.2Entry temperature to compressorC-15.0-4.3Discharge temperatureC83.0121.438.4Compression ratio9.813.8Total power inputkW0.730.70Swept volumem^3 / h4.104.53System Suction specific volumekJ / m^3790.7715.590.5COP cooling1.41.4Mass flow ratekg / s0.008980.0061568.4

[0129] Although Blend 7 has a much lower GWP than R404A, and its maximum (discharge) pressure is acceptable as a retrofit for R404A, the model results indicated that the performance of Blend 7 was inferior to R404A in certain key respects.

[0130] The compressor discharge temperature is 38.4 °< C higher for Blend 7 than for R404A which would seriously reduce reliability and operating life of the compressor. The mass flow rate of Blend 7 is 68.4% lower than for R404A, so for a freezer, or other refrigeration unit with a fixed capillary tube expansion device, the flow rate of Blend 7 would be too large, and would potentially flood the evaporator, which may result in too high an evaporation temperature and also flooding of the evaporator which in turn could result in liquid returning to the compressor, which may cause damage.

[0131] The very wide evaporator glide of 13.5 K resulted in the evaporator refrigerant exit temperature (-18.4 °< C) being above the maximum temperature needed to maintain frozen food below -18 °< C.

[0132] The very wide condenser glide of Blend 7 (25.1 K) resulted in a condenser exit temperature of 17.5 °< C compared to 29.9 °< C for R404A. On the basis that the exit temperature needed to be at least approximately 5 K above the ambient air temperature to ensure for adequate heat transfer from the refrigerant to the air, then R404A may need to be cooled by ambient air at 25 °< C and below, while Blend 7 would only work if the ambient temperature was below 12 °< C - an unrealistic value for a commercial freezer cabinet in a supermarket.

[0133] The calculated suction cooling capacity of Blend 7 was only 68.4%. This indicated that R404A would not be able to maintain food in the required temperature range of -23 °< C to -18 °< C, especially at high ambient. The calculations predicted that Blend 7 could not be a retrofit replacement for R404A. Surprisingly, we have found that Blend 7 is a good retrofit for R404A in a real unit, contrary to what swas predicted using the conventional calculations.

[0134] An AHT freezer display cabinet, Model Paris 250(-) type LE228, containing 0.276 kg R404A, was loaded with 182 kg of ice contained in 50 × 1.5 L, 1 × 3 L and 13 × 8 L plastic bottles to simulate typical freezer contents. The freezer was run until it reached, and maintained, a steady temperature, as recorded by its in-built temperature sensor. The ambient air temperature, the compressor gas discharge temperature, the suction pressure, the discharge pressure, the suction gas temperature, just before the compressor, and the current draw by the unit were also measured. The results are recorded in Table 6 after the freezer had been operating for 29.7 hours.

[0135] The R404A was then replaced by a similar weight of Blend 7 and the results recorded after 29.8 hours of operation Table 6R404ABlend 7Room temperature°C14.214.0Refrigerant suction temperature°C16.817.0Refrigerant discharge temperature°C68.971.1Freezer temperature (unit thermostat)°C-25.5-28.0Temperature top of freezer°C-22.0-21.2Suction pressurebarg-0.020.13Discharge pressurebarg11.814.1Current drawamp2.392.66Running timehour29.729.8

[0136] The results show that Blend 7 is able to maintain the freezer temperature at, or below, its design rating of -18 to -23°C achieved with R404A. The fact that Blend 7 maintained a lower temperature than R404A indicates that it has a better cooling capacity than R404A, and thus will be acceptable for high ambient temperatures.

[0137] Surprisingly, the discharge temperature of Blend 7 was only 2.2°C higher than that of R404A, in contrast to the much greater difference predicted from the model calculation.

[0138] Although the current draw (a measure of the electrical power input) is about 11% higher for Blend 7, this is acceptable.

[0139] The operating period of 29.8 hours showed that Blend 7 had reached a steady state and there was no indication of malfunctioning that might be associated with a flooded evaporator problem.Example 4

[0140] The performances of Blends 8 to 12, whose compositions are shown in Table 7, were modelled for a typical low temperature refrigeration system using a Rankine Cycle program with thermodynamic data generated by NIST's REFPROP v10. The performance of R404A is included for comparison. The results in Table 7 indicate that these novel blends are acceptable replacements for retrofitting in R404A equipment. Table 7Blend 8Blend 9Blend 10Blend 11Blend 12R404AComponent R1250.110.130.120.140.140.44R143a000000.52R134a0.030.030.050.030.050.04carbon dioxide0.110.110.090.110.110R1234yf000.300.480R227ea0.070.070.050.070.080R1234ze0.570.530.280.5100R320.110.130.110.140.140GWP7017776908168723943Results InputCooling dutykW111111Condenser MidpointC353535353535SubcoolK555555Evaporator MidpointC-35-35-35-35-35-35SuperheatC555555Compressor Isentropic efficiency0.70.70.70.70.70.7Electric motor efficiency0.90.90.90.90.90.9Volumetric efficiency0.90.90.90.90.90.9Output CondenserPressurebara16.617.317.117.620.116.12Dew pointC47.947.445.347.144.535.2Bubble pointC22.122.624.722.925.534.8Mid pointC353535353535.00GlideK25.724.820.524.319.00.4Exit temperatureC17.117.619.717.920.529.8Evaporator Pressurebara1.201.281.341.321.741.65Entry temperatureC-42.0-42.1-40.3-42.1-40.2-35.2Dew pointC-28.0-27.9-29.7-27.9-29.8-34.8Mid pointC-35-35-35-35-35-35GlideK13.9314.2010.6314.2610.480.5Exit temperatureC-23.0-22.9-24.7-22.9-24.8-29.8Compressor Entry temperature to casingC-23.0-22.9-24.7-22.9-24.8-29.8Entry temperature to compressorC-9.3-9.0-12.0-8.9-12.1-20.2Discharge temperatureC116.2117.8106.2118.5107.577.4Compression ratio13.813.412.713.311.69.75Total power inputkW0.700.710.710.710.730.74Swept volumem^3 / h4.494.264.274.163.494.15SystemSuction specific volumekJ / m^3721760759779927780COP cooling1.421.421.401.411.371.36Mass flow ratekg / s0.006260.006230.006870.006220.007010.00933

Claims

1. A refrigerant composition consisting essentially of: carbon dioxide1-35%an HFO selected from the group consisting of: R1234yf and R1234ze(E) and mixtures thereof,30-92%R321-30%R1251-30%R227ea1-15%R134a0-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

2. A refrigerant composition, as claimed in claim 1, consisting essentially of: carbon dioxide5-20%an HFO selected from the group consisting of: R1234yf and R1234ze(E) and mixtures thereof,30-92%R325-30%R1255-30%R227ea1-15%R134a0-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

3. A refrigerant composition, as claimed in claim 1, consisting essentially of: R1256-23%carbon dioxide6-20%R1234ze55-68%R227ea2-15%R326-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

4. A refrigerant composition, as claimed in claim 3, consisting essentially of: R1256-20%carbon dioxide6-18%R1234ze55-67%R227ea3-15%R327-20% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

5. A refrigerant composition, as claimed in claim 4, consisting essentially of: R1259.5%carbon dioxide8%R1234ze65%R227ea8%R329.5% wherein the percentages are by mass.

6. A refrigerant composition, as claimed in claim 1, consisting essentially of one of the following compositions: (a) R1259.5%carbon dioxide9%R1234ze57%R227ea15%R329.5% wherein the percentages are by mass. (b) R1259.5%carbon dioxide9%R1234ze58%R227ea14%R329.5% wherein the percentages are by mass. (c) R12519%carbon dioxide16%R1234ze41%R227ea5%R3219% wherein the percentages are by mass.

7. A refrigerant composition, as claimed in claim 1, consisting essentially of: R12512-23%carbon dioxide8-20%R1234ze35-55%R227ea3-10%R3212-23% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

8. A refrigerant composition, as claimed in claim 1, consisting essentially of one of the following compositions: (a) R1259.5%carbon dioxide9%R1234ze58%R227ea7%R329.5%R134a7% wherein the percentages are by mass. (b) R12511%carbon dioxide11%R1234ze57%R227ea7%R3211%R134a3% wherein the percentages are by mass. (c) R12518%carbon dioxide11%R1234ze44%R227ea6%R3217%R134a4% wherein the percentages are by mass. (d) R12511%carbon dioxide11%R1234ze55%R227ea7%R3211%R134a5% wherein the percentages are by mass. (e) R12513%carbon dioxide11%R1234ze53%R227ea7%R3213%R134a3% wherein the percentages are by mass. (f) R12513%carbon dioxide11%R1234ze55%R227ea7%R3213%R134a1% wherein the percentages are by mass. (g) R12514%carbon dioxide11%R1234ze51%R227ea7%R3214%R134a3% wherein the percentages are by mass. (h) R12514%carbon dioxide11%R1234ze55%R227ea7%R3213% wherein the percentages are by mass. (i) R12510.5%carbon dioxide11%R1234ze57%R227ea7%R3210.5%R134a4% wherein the percentages are by mass. (j) R12510.5%carbon dioxide11%R1234ze58%R227ea7%R3210.5%R134a3% wherein the percentages are by mass. (k) R12511.5%carbon dioxide10%R1234ze57%R227ea7%R3211.5%R134a3% wherein the percentages are by mass. (l) R12511.5%carbon dioxide10%R1234ze56%R227ea8%R3211.5%R134a3% wherein the percentages are by mass.

9. A refrigerant composition, as claimed in claim 1, consisting essentially of one of the following compositions: (a) R12519%carbon dioxide10%R1234ze44%R227ea3%R3217%R134a7% wherein the percentages are by mass. (b) R12518%carbon dioxide11%R1234ze44%R227ea7%R3217%R134a3% wherein the percentages are by mass. (c) R12518%carbon dioxide11%R1234ze44%R227ea6%R3217%R134a4%10. A refrigerant composition, as claimed in claim 1, consisting essentially of one of the following compositions: (a) R1251-30%carbon dioxide1-30%R1234yf35-70%R227ea1-10%R321-30% wherein the percentages are by mass and are selected from the ranges quoted to total 100%. (b) R1255-30%carbon dioxide5-20%R1234yf35-70%R227ea4-10%R325-30%11. A refrigerant composition, as claimed in claim 1, consisting essentially of: R1257-25%carbon dioxide7-20%R1234yf58-69%R227ea5-10%R327-25% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

12. A refrigerant composition, as claimed in claim 1, consisting essentially of: R1259.5%carbon dioxide8%R1234yf65%R227ea8%R329.5% wherein the percentages are by mass.

13. A refrigerant composition, as claimed in claim 1, consisting essentially of: R12519%carbon dioxide16%R1234yf41%R227ea5%R3219% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.

14. A refrigerant composition, as claimed in claim 1, consisting essentially of: R12519%carbon dioxide16%R1234ze20%R1234yf21%R227ea5%R3219% wherein the percentages are by mass.

15. A refrigerant composition consisting essentially of: carbon dioxide1-35%an HFO selected from the group consisting of R1234yf, R1234ze(E) and mixtures thereof,30-95%R321-30%R1251-30%R134a1-15%R227ea1-15% wherein the percentages are by mass and are selected from the ranges quoted to total 100%.