Non-flammable refrigerants having a low GWP, and systems and methods for providing refrigeration

Abstract

The present invention provides a cascade refrigeration system in which the low stage contains a refrigerant having a GWP of less than 150, the high stage is either class A1 or class A2L, and contains a refrigerant including at least about 75 wt% of HFO-1234ze(E).

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This invention relates to U.S. Provisional Application No. 63 / 454,325, filed on March 24, 2023, and U.S. Provisional Application No. 63 / 344,540, filed on May 21, 2022, each of which is incorporated herein by reference in its entirety as if fully set forth below, and claims the benefit of their priorities.

[0002] (Field of the Invention) The present invention relates to high - efficiency, low global warming potential ( "low GWP") refrigerants, and in particular to air - conditioning and / or refrigeration systems or methods for providing cooling, including a cascade refrigeration system that is safe and effective.

Background Art

[0003] The refrigeration industry is increasingly being pressured to replace high global warming potential (GWP) refrigerants such as R134a and R404A with low GWP refrigerants such as those having a GWP of less than 150. This is particularly important in commercial refrigeration systems where large amounts of refrigerant are used.

[0004] One approach is to use low-GWP refrigerants such as carbon dioxide (R744) refrigerant and hydrocarbon refrigerants. However, such approaches that have been used so far have several significant safety and financial drawbacks, including increased operating costs due to low system energy efficiency, increased initial system costs due to high system complexity, increased maintenance costs due to low system utility and reliability, and high flammability of the system. A system containing a highly flammable refrigerant according to a conventional configuration can be particularly disadvantageous because it can result in a lower level of safety, conflict with regulatory constraints, and increase the liability of refrigeration system operators and manufacturers. Given that many commercial refrigeration applications such as supermarket refrigerators, freezers, and refrigerated display cases are publicly available and often operate in locations with high population density, safety is of particular concern.

[0005] Therefore, the applicants understood that the refrigeration industry continues to need a safe, robust, and sustainable approach to reducing the use of high-GWP refrigerants that can be used with existing technologies.

[0006] One such approach that has been used previously is shown in FIG. 1A. FIG. 1A shows a refrigeration system 100 commonly used for commercial refrigeration in a supermarket. System 100 is a direct expansion system that provides both medium-temperature refrigeration and low-temperature refrigeration via a medium-temperature refrigeration circuit 110 and a low-temperature refrigeration circuit 120.

[0007] In a typical conventional configuration labeled 100 in FIG. 1A, the medium-temperature refrigeration circuit 110 has R134a as its refrigerant. The medium-temperature refrigeration circuit 110 provides both medium-temperature cooling and removes waste heat from the lower-temperature refrigeration circuit 120 via the heat exchanger 130. The medium-temperature refrigeration circuit 110 extends between the roof 140, the machine room 141, and the sales floor 142. On the other hand, the low-temperature refrigeration circuit 120 has R744 as its refrigerant. The low-temperature refrigeration circuit 120 extends between the machine room 141 and the sales floor 142. Advantageously, as discussed above, R744 has a low GWP.

[0008] However, while a refrigeration system of the type disclosed in FIG. 1A may be capable of providing a good level of efficiency, the applicants understand that such a system has at least two main drawbacks, namely, firstly, that such a system uses the high-GWP refrigerant R134a (R134a having a GWP of approximately 1300), and secondly, that even when the low-temperature portion of such a system uses the low-GWP refrigerant R744, this refrigerant exhibits a number of the drawbacks discussed above, including significant safety and financial drawbacks.

[0009] Furthermore, in certain refrigeration applications, it is necessary to cool articles without exposing them to temperatures below a specific temperature, such as the freezing point of water. For example, in a supermarket environment, it is common to keep certain products at a lower temperature relative to the surroundings. At the same time, particularly since the preferred method of cooling involves indirect cooling by humid air or ambient air, it is disadvantageous to cool the products below the freezing point of water. For these applications, having a refrigerant temperature below the freezing point of water along the evaporator is also disadvantageous because it causes frost accumulation, resulting in the need to defrost the equipment. Avoiding frost accumulation is an important aspect in those applications. Similarly, the cooling of beverages containing water, etc. should also be carried out under conditions that avoid exposing such products to temperatures below the freezing point of water because freezing of such products is not desirable at the point of sale. For convenience, the applicants refer to such applications, methods, and systems as "non-freezing" applications, methods, and systems herein.

[0010] Certain single-component fluorocarbons, including chlorofluorocarbons ("CFCs"), hydrochlorofluorocarbons ("HCFCs"), and hydrofluorolefins ("HFOs"), are used in "frost-free" applications where the refrigerant temperature along the evaporator must be maintained above the freezing point of water so that frost does not accumulate on the coil surface and, as a result, defrosting is unnecessary. In such refrigeration applications, systems, and methods, the use of a single-component fluid has heretofore been considered particularly desirable because the saturation temperature of such a fluid does not change upon evaporation of the fluid at a constant pressure. The use of a single-component fluid is very desirable to enable the design of systems and methods using a refrigerant temperature along the evaporator that is essentially constant during the evaporation process, assuming little or no pressure drop as the refrigerant flows through the evaporator, and that exceeds the freezing point of water. In addition, product applications typically also require a small temperature difference between the air and the refrigerant in order to dehumidify the air and as a result reduce the removal of moisture content and loss of product quality. The combination of the need for the evaporator to have a specific positive superheat at the outlet, the small temperature difference, and the requirement to avoid frost formation can be important in selecting a specific refrigerant for such applications. A superheat of zero or less, i.e., where the refrigerant is not superheated, can lead to reduced cooling capacity, efficiency, and potential compressor failure. The term "superheat" or simply "superheated" means the temperature rise of the refrigerant at the outlet of the evaporator above the saturation vapor temperature (or dew point temperature) of the refrigerant.

[0011] This is illustrated as an example in FIG. 1B, which represents in schematic form a typical supermarket product cooling case. Typically, as illustrated in FIG. 1, air having cooled moisture is provided to the product display zone of the display case by passing air from both outside the case 102 and the recirculation air 104 over the heat exchange surface of an evaporator coil 106 disposed within the display case in a region that is typically separate from (or at least hidden from the consumer's view) but proximate to the product display zone. The evaporator 106 has a single component refrigerant inlet 108 and a single component refrigerant outlet 110. A circulation fan 114 is also used. It is highly desirable in systems of the type illustrated above for the cooling space 112 within the refrigeration system to have a refrigerant temperature along the evaporator that always or substantially always exceeds a constant level. For example, in many applications such as the refrigeration of products, the minimum discharge (outlet) temperature of the air within the display case is set by design to be about 2° C. to 3° C. in order to provide a safety margin to avoid having a cooling space or cooled article with a temperature below the freezing point of water. Additionally, in order to minimize the removal of moisture from the air and the resulting drying (quality loss) of the product, the temperature difference between the air outlet and the refrigerant needs to be small, typically 2° C. to 3° C. This, in combination with the fact that evaporators for these applications require a superheat of about 3 to about 5° C., will impose constraints on the allowable evaporator glide of the refrigerant such that the evaporation temperature remains above the freezing point of water and, as a result, frost does not accumulate.

[0012] One of ordinary skill in the art will appreciate that it has heretofore often been very difficult to provide a refrigerant that is a multi-component blend of different single component refrigerants for these two desirable results.

[0013] Prior to the present invention, those skilled in the art, as discussed above, have primarily utilized single-component refrigerants such as HFC-134a in such applications having low temperature sensitivity, and have avoided refrigerant blends because blends generally undergo significant changes in boiling point temperature upon evaporation, which has been conventionally recognized as a major obstacle to the ability to identify blends having the correct balance of properties useful in such systems.

[0014] On the other hand, the applicants have come to understand that it is also difficult to identify single-component fluids having a set of properties that provide specific advantages in applications of the type discussed above. For example, in many important applications, it is necessary to identify a refrigerant that simultaneously satisfies the following: (1) has an effective glide, i.e., has a glide of less than 4.5°C, preferably less than about 4°C, and even more preferably less than about 3°C, to avoid frost formation and is capable of maintaining a typical superheat, e.g., from about 3°C to about 5°C; (2) is non-flammable (Class A1) or slightly flammable (Class A2L); (3) is of low toxicity or substantially non-toxic; (4) has a low global warming potential (GWP) (e.g., less than about 150); and (5) has heat transfer and other properties (such as chemical stability) that match the requirements of a particular application, particularly in medium-temperature heat transfer systems, and even more preferably in frost-free or low-frost medium-temperature refrigeration systems. The use of single-component refrigerants can often satisfy items (1), (2), and (3), but those skilled in the art have found that it is (if not impossible) difficult to conventionally find a refrigerant (single-component or otherwise) that can satisfy not only items (1), (2), and (3), but also most and preferably all of items (4)-(5). Here, non-flammable substances are classified as Class "1" by ASHRAE, and low-toxicity substances are classified as Class "A" by ASHRAE Standard 34-2016. Substances that are non-flammable and of low toxicity are classified as "A1" by ASHRAE Standard 34-2016.

[0015] For example, HFC-134a has been conventionally used for certain non-freezing applications, but nevertheless, since HFC-134a has a GWP of about 1300, it does not meet, for example, the low GWP requirement (item 5 above).

[0016] The applicants have proceeded in a manner contrary to common general knowledge and discovered unexpected and advantageous results. For example, as will be described in detail below, the applicants have found that a particular blend containing a carefully selected combination of components can have an advantageous but unexpected non-flammable combination, and at the same time, in particular, has excellent heat transfer characteristics, a low GWP (e.g., a GWP of less than about 150), low toxicity or non-toxicity, chemical stability, and lubricant compatibility. Furthermore, the applicants have found that the refrigerant composition of the present invention protects articles being cooled from frost and / or prevents frosting of the evaporator coil, and thus, in a medium-temperature refrigeration system, particularly a medium-temperature refrigeration system within a cascade refrigeration system, and / or a medium-temperature refrigeration system where it is desirable to maintain the cooled air temperature above about 0 °C and avoid exposing the cooled air to a temperature below about 0 °C. Frosting of the evaporator coil itself can adversely affect the overall efficiency of such a system due to the need for defrosting and / or non-uniform cooling across the coil. SUMMARY OF THE INVENTION

[0017] The present applicants have found a refrigerant composition, a heat transfer composition containing a refrigerant, a refrigeration method and system including a cascade heat transfer method and system, and / or a method and system for cooling materials having low-temperature constraints such as the above-described low-freezing or non-freezing applications.

[0018] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system comprises (a) a low-stage refrigeration circuit comprising a low-stage refrigerant having a GWP of about 150 or less, and a compressor, the low-stage refrigeration circuit; (b) an inter-circuit heat exchanger where the low-stage refrigerant condenses; (c) A high-stage refrigeration circuit containing a high-stage refrigerant, where the high-stage refrigerant: (i) has a flammability of Class A1 or Class A2L; (ii) evaporates at a temperature below the condensation temperature of the low-stage refrigerant; (iii) contains at least about 77% by weight of HFO-1234ze(E), and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit, a high-stage refrigeration circuit, and a cascade refrigeration system including the same.

[0019] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 1A".

[0020] The present invention relates to a cascade refrigeration system, where the cascade refrigeration system (a) A low-stage refrigeration circuit, where (i) a low-stage refrigerant having a GWP of about 150 or less and a flammability of Class A1 or Class A2L, and (ii) a low-stage refrigeration circuit including a compressor, (b) An inter-circuit heat exchanger where the low-stage refrigerant condenses, (c) A high-stage refrigeration circuit containing a high-stage refrigerant, where the high-stage refrigerant: (i) has a flammability of Class A1 or Class A2L; (ii) evaporates at a temperature below the condensation temperature of the low-stage refrigerant; (iii) contains at least about 77% by weight of HFO-1234ze(E), and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit, a high-stage refrigeration circuit, and a cascade refrigeration system including the same.

[0021] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 1B".

[0022] The present invention relates to a cascade refrigeration system, where the cascade refrigeration system (a) A low-stage refrigeration circuit, where (iii) a low-stage refrigerant having a GWP of about 150 or less and a flammability of Class A2L or Class A1, and (iv) a low-stage refrigeration circuit including a compressor, (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses, and (c) A high-stage refrigeration circuit containing a high-stage refrigerant, wherein the high-stage refrigerant (i) has a flammability of Class A1, (ii) evaporates at a temperature lower than the condensation temperature of the low-stage refrigerant, (iii) contains at least about 77 wt% of HFO-1234ze(E), and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit, and a high-stage refrigeration circuit, comprising a cascade refrigeration system.

[0023] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 1C".

[0024] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system (a) A low-stage refrigeration circuit, wherein (i) A low-stage refrigerant consisting essentially of propane, and (ii) A low-stage refrigeration circuit including a compressor, (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses, and (c) A high-stage refrigeration circuit containing a high-stage refrigerant, wherein the high-stage refrigerant (i) has a flammability of Class A1, (ii) evaporates at a temperature lower than the condensation temperature of the low-stage refrigerant, (iii) contains at least about 77 wt% of HFO-1234ze(E), and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit, and a high-stage refrigeration circuit, comprising a cascade refrigeration system.

[0025] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 2A".

[0026] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system (a) A low-stage refrigeration circuit, wherein (i) A low-stage refrigerant consisting essentially of R454C, and (ii) A low-stage refrigeration circuit including a compressor, (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses, and (c) A high-stage refrigeration circuit containing a high-stage refrigerant, wherein the high-stage refrigerant (i) has a flammability of Class A1, (ii) evaporates at a temperature below the condensation temperature of the low-stage refrigerant, (iii) contains at least about 77% by weight of HFO-1234ze(E), and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit, and a high-stage refrigeration circuit, comprising a cascade refrigeration system.

[0027] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 2B".

[0028] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system (a) A low-stage refrigeration circuit, wherein (i) A low-stage refrigerant consisting essentially of R455A, and (ii) A compressor, a low-stage refrigeration circuit. (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses; and (c) A high-stage refrigeration circuit containing a high-stage refrigerant, wherein the high-stage refrigerant (i) has a flammability of Class A1, (ii) evaporates at a temperature below the condensation temperature of the low-stage refrigerant, (iii) contains at least about 77% by weight of HFO-1234ze(E), and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit, and a high-stage refrigeration circuit, comprising a cascade refrigeration system.

[0029] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 2C1".

[0030] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system (a) A low-stage refrigeration circuit, wherein (i) A low-stage refrigerant consisting essentially of R455A, (ii) A compressor, (iii) A condenser, (iv) An evaporator, and (v) A low-stage refrigeration circuit including an intake line heat exchanger connected between an outlet of the evaporator and an inlet of the compressor for transferring heat to the refrigerant entering the compressor, (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses, (c) A high-stage refrigeration circuit including a high-stage refrigerant, wherein the high-stage refrigerant (i) has a flammability of Class A1, (ii) evaporates at a temperature below the condensation temperature of the low-stage refrigerant, (iii) contains at least about 77 wt% of HFO-1234ze(E), and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit. A cascade refrigeration system comprising a high-stage refrigeration circuit,

[0031] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 2C2".

[0032] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system (a) A low-stage refrigeration circuit, (i) A low-stage refrigerant consisting essentially of R455A, (ii) A compressor, (iii) A condenser, (iv) An evaporator, and (v) A low-stage refrigeration circuit including an intake line heat exchanger connected between an outlet of the evaporator and an inlet of the compressor for transferring heat to the refrigerant entering the compressor, (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses, (c) A high-stage refrigeration circuit including a high-stage refrigerant, wherein the high-stage refrigerant consists essentially of R471A, evaporates at a temperature below the condensation temperature of the low-stage refrigerant, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit. A cascade refrigeration system comprising a high-stage refrigeration circuit,

[0033] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 2C3".

[0034] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system comprises: (a) A low-stage refrigeration circuit, comprising: (i) A low-stage refrigerant consisting essentially of R455A; (ii) A compressor; (iii) A condenser; (iv) An evaporator; and (v) An intake line heat exchanger connected between the outlet of the evaporator and the inlet of the compressor for transferring heat to the refrigerant entering the compressor; (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses; (c) A high-stage refrigeration circuit, comprising: i. A high-stage refrigerant that (1) has a flammability of Class A1, (2) evaporates at a temperature lower than the condensation temperature of the low-stage refrigerant, and (3) contains at least about 77% by weight of HFO-1234ze(E), and wherein the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit; ii. A compressor; iii. A condenser; iv. An evaporator; and v. An intake line heat exchanger connected between the outlet of the evaporator and the inlet of the compressor for transferring heat to the refrigerant entering the compressor.

[0035] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 2C4".

[0036] The present invention is a cascade refrigeration system, wherein the cascade refrigeration system comprises: (a) A low-stage refrigeration circuit, comprising: (i) A low-stage refrigerant consisting essentially of R455A; (ii) A compressor; (iii) A condenser; (iv) An evaporator; and (v) An intake line heat exchanger connected between the outlet of the evaporator and the inlet of the compressor for transferring heat to the refrigerant entering the compressor. (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses, and (c) A high-stage refrigeration circuit, i. A high-stage refrigerant that consists essentially of R471A, evaporates at a temperature lower than the condensation temperature of the low-stage refrigerant, and evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit, ii. A compressor, iii. A condenser, iv. An evaporator, and v. An intake line heat exchanger connected between the outlet of the evaporator and the inlet of the compressor and configured to transfer heat to the refrigerant entering the compressor, and a high-stage refrigeration circuit, and a cascade refrigeration system including the same.

[0037] For convenience purposes, the system according to this paragraph may be referred to herein as "System 2C5" in some cases.

[0038] The present invention also relates to a cascade refrigeration system, wherein the cascade refrigeration system includes (a) A plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit including (i) A low-stage refrigerant consisting essentially of propane, and (ii) A compressor, and a low-stage refrigeration circuit, (b) An inter-circuit heat exchanger in which the low-stage refrigerant condenses, preferably within a temperature range of about -5°C to about -15°C, and (c) A high-stage refrigeration circuit including an A1 refrigerant containing 78 wt% to 79 wt% of HFO-1234ze(E), 16.5 wt% to 17.5 wt% of HFO-1336mzz(E), and 4 wt% to 5 wt% of HFC-227ea, wherein the high-stage refrigerant evaporates at a temperature lower than the condensation temperature of the low-stage refrigerant, preferably within a range of about -5°C to about -15°C, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the low-stage refrigerant, and a cascade refrigeration system including the same.

[0039] For convenience purposes, the system according to this paragraph may be referred to herein as "System 3A1" in some cases.

[0040] The present invention also relates to a cascade refrigeration system, wherein the cascade refrigeration system comprises (a) a low-stage refrigeration circuit comprising (i) a low-stage refrigerant consisting essentially of propane, and (ii) a compressor, (b) an inter-circuit heat exchanger in which the low-stage refrigerant condenses preferably within a temperature range of about -5°C to about -15°C, and (c) a high-stage refrigeration circuit, wherein the high-stage refrigerant consists essentially of R-471A, the high-stage refrigerant evaporates at a temperature below the condensation temperature of the low-stage refrigerant, preferably within a range of about -5°C to about -15°C, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the low-stage refrigerant.

[0041] For convenience purposes, the system according to this paragraph is optionally referred to herein as "System 3B".

[0042] The present invention also relates to a cascade refrigeration system, wherein the cascade refrigeration system comprises (a) a low-stage refrigeration circuit comprising (i) a low-stage A2L refrigerant containing 75% to 80% by weight of HFO-1234yf and 21% to 22% by weight of HFC-32, and (ii) a compressor, (b) an inter-circuit heat exchanger in which the low-stage refrigerant condenses preferably within a temperature range of about -5°C to about -15°C, and (c) A high-stage refrigeration circuit comprising an A1 refrigerant containing 78% to 79% by weight of HFO-1234ze(E), 16.5% to 17.5% by weight of HFO-1336mzz(E), and 4% to 5% by weight of HFC-227ea, wherein the high-stage refrigerant evaporates at a temperature below the condensation temperature of the low-stage refrigerant, preferably in the range of about -5°C to about -15°C, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the low-stage refrigerant, and a high-stage refrigeration circuit, and a cascade refrigeration system comprising the same.

[0043] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 4A".

[0044] The present invention also relates to a cascade refrigeration system, wherein the cascade refrigeration system comprises (a) A plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising (i) A low-stage A2L refrigerant containing 75% to 80% by weight of HFO-1234yf and 21% to 22% by weight of HFC-32, and (ii) A compressor, and a low-stage refrigeration circuit, (b) An inter-circuit heat exchanger, wherein the low-stage refrigerant condenses preferably within a temperature range of about -5°C to about -15°C, and an inter-circuit heat exchanger, (c) A high-stage refrigeration circuit, wherein the high-stage refrigerant consists essentially of R471A, the high-stage refrigerant evaporates at a temperature below the condensation temperature of the low-stage refrigerant, preferably in the range of about -5°C to about -15°C, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the low-stage refrigerant, and a high-stage refrigeration circuit, and a cascade refrigeration system comprising the same.

[0045] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 4B".

[0046] The present invention also relates to a cascade refrigeration system, wherein the cascade refrigeration system comprises (a) A plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising (i) A low-stage A2L refrigerant containing 78% to 79% by weight of HFO-1234yf and 21% to 22% by weight of HFC-32, and (ii) A low-stage refrigeration circuit including a compressor, and (b) An inter-circuit heat exchanger, wherein the low-stage refrigerant preferably condenses within a temperature range of about -5°C to about -15°C, and (c) A high-stage refrigeration circuit including an A1 refrigerant containing 78% to 79% by weight of HFO-1234ze(E), 16.5% to 17.5% by weight of HFO-1336mzz(E), and 4% to 5% by weight of HFC-227ea, wherein the high-stage refrigerant evaporates at a temperature below the condensation temperature of the low-stage refrigerant, preferably within a temperature range of about -5°C to about -15°C, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the low-stage refrigerant. A cascade refrigeration system comprising the above components is provided.

[0047] For convenience purposes, the system according to this paragraph may optionally be referred to herein as "System 4C".

[0048] The present invention also relates to a cascade refrigeration system, wherein the cascade refrigeration system comprises (a) A plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising (i) A low-stage refrigerant consisting essentially of R454C, and (ii) A compressor, and (b) An inter-circuit heat exchanger, wherein the low-stage refrigerant preferably condenses within a temperature range of about -5°C to about -15°C, and (c) A high-stage refrigeration circuit including an A1 refrigerant containing 78% to 79% by weight of HFO-1234ze(E), 16.5% to 17.5% by weight of HFO-1336mzz(E), and 4% to 5% by weight of HFC-227ea, wherein the high-stage refrigerant evaporates at a temperature below the condensation temperature of the low-stage refrigerant, preferably within a temperature range of about -5°C to about -15°C, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the low-stage refrigerant. A cascade refrigeration system comprising the above components is provided.

[0049] For the purpose of economy, the system according to this paragraph may be referred to herein as "System 4D" in some cases.

[0050] The present invention also relates to a cascade refrigeration system, wherein the cascade refrigeration system comprises (a) a plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising (i) a low-stage refrigerant consisting essentially of R454C, and (ii) a compressor, (b) an inter-circuit heat exchanger, wherein the low-stage refrigerant preferably condenses within a temperature range of about -5°C to about -15°C, (c) a high-stage refrigeration circuit, comprising a refrigerant consisting essentially of R-471A, wherein the high-stage refrigerant evaporates at a temperature lower than the condensation temperature of the low-stage refrigerant, preferably within a range of about -5°C to about -15°C, and the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the low-stage refrigerant.

[0051] For the purpose of economy, the system according to this paragraph may be referred to herein as "System 4E" in some cases.

[0052] The present invention relates to a cascade refrigeration system, including each of Systems 1 to 4, wherein the low-stage refrigeration circuit comprises a plurality of low-stage refrigeration circuits. For the purpose of economy, the system according to this paragraph may be referred to herein as "System 5A" in some cases.

[0053] The present invention relates to a cascade refrigeration system, including each of Systems 1 to 4, wherein the low-stage refrigeration circuit is arranged in a publicly available area. For the purpose of economy, the system according to this paragraph may be referred to herein as "System 5B" in some cases.

[0054] The present invention is a cascade refrigeration system, including each of systems 1 to 4, wherein the low-stage refrigeration circuit includes a plurality of built-in low-stage refrigeration circuits, and at least two of such low-stage circuits are contained within separate modular refrigeration units, and each of the modular refrigeration units is arranged in a first region that is publicly available, including a cascade refrigeration system. For convenience purposes, the system according to this paragraph is sometimes referred to as "System 5C" in this specification.

[0055] The present invention is a cascade refrigeration system, including each of systems 1 to 5, wherein the compressor in each of the low stages has a horsepower rating of about 2 horsepower or less, including a cascade refrigeration system. For convenience purposes, the system according to this paragraph is sometimes referred to as "System 6" in this specification.

[0056] The present invention is a cascade refrigeration system, including each of systems 1 to 6, wherein in the inter-circuit heat exchanger, the low-stage refrigerant condenses within a temperature range of about -5°C to about -15°C, including a cascade refrigeration system. For convenience purposes, the system according to this paragraph is sometimes referred to as "System 7" in this specification.

[0057] The present invention is a method for providing heating and / or cooling, a. providing a vapor compression refrigeration system including a compressor, a condenser, an evaporator, and a refrigerant, i. 65 wt% to less than 85 wt% of HFO-1234ze(E), ii. 3.5 wt% to 5.5 wt% of HFC-227ea, and iii. about 15 wt% to about 22 wt% of HFO-1336mzz(E), b. evaporating the refrigerant in the evaporator, wherein the glide of the refrigerant in the evaporator is 3°C or less, and the refrigerant has a capacity within the system that is at least about 60% of the capacity of R-134a within the system, including a method.

[0058] The method according to this paragraph is optionally referred to herein as "heat transfer method 1" for convenience.

[0059] The present invention provides a method for providing heating or cooling, a. a compressor, a condenser, an evaporator, and a refrigerant comprising i. 75 wt% to less than 85 wt% of HFO-1234ze(E), ii. 3.5 wt% to 5.5 wt% of HFC-227ea, and iii. about 15 wt% to about 20 wt% of HFO-1336mzz(E), and a vapor compression refrigeration system comprising the refrigerant, b. evaporating the refrigerant in the evaporator, wherein the glide of the refrigerant in the evaporator is 3°C or less and the refrigerant has a capacity in the system that is at least about 60% of the capacity of R-134a in the system.

[0060] The method according to this paragraph is optionally referred to herein as "heat transfer method 2" for convenience.

[0061] The present invention provides a method for providing cooling, a. a compressor, a condenser, an evaporator, and a refrigerant comprising i. 65 wt% to less than 85 wt% of HFO-1234ze(E), ii. less than 12 wt% of HFC-134a, and iii. about 10 wt% to about 22 wt% of HFO-1336mzz(E), and a vapor compression refrigeration system comprising the refrigerant, b. evaporating the refrigerant in the evaporator, wherein the refrigeration system is selected from a high-temperature heat pump system and an air-conditioning system at extreme temperatures. The method according to this paragraph is optionally referred to herein as "heat transfer method 3A" for convenience.

[0062] The present invention provides a method for providing cooling, a. a compressor, a condenser, an evaporator, and a refrigerant comprising i. Approximately 78.7 wt% of HFO-1234ze(E), ii. Approximately 4.3 wt% of HFC-227ea, and iii. Providing a vapor compression refrigeration system comprising a refrigerant comprising approximately 17 wt% of HFO-1336mzz(E), evaporating the refrigerant in the evaporator, wherein the refrigeration system is selected from a high temperature heat pump system and an air conditioning system at extreme temperatures. The method according to this paragraph is optionally referred to herein as "heat transfer method 3B" for convenience.

[0063] The present invention is a method of providing cooling, a. A compressor, a condenser, an evaporator, and a refrigerant comprising i. Approximately 78.7 wt% of HFO-1234ze(E), ii. Approximately 4.3 wt% of HFC-227ea, and iii. A refrigerant consisting essentially of approximately 17 wt% of HFO-1336mzz(E), b. evaporating the refrigerant in the evaporator, wherein the refrigeration system is selected from a high temperature heat pump system and an air conditioning system at extreme temperatures. The method according to this paragraph is optionally referred to herein as "heat transfer method 3C" for convenience.

[0064] The present invention is a method of providing cooling, a. A compressor, a condenser, an evaporator, and a refrigerant comprising i. Approximately 78.7 wt% + 0.4 / -1.5 wt% of HFO-1234ze(E), ii. Approximately 4.3 wt% + 1.5 / -0.4 wt% of HFC-227ea, and iii. Consisting of approximately 17 wt% + 1.5 / -0.4 wt% of HFO-1336mzz(E), a refrigerant, b. evaporating the refrigerant in the evaporator, The method includes a refrigeration system being selected from a high-temperature heat pump system and an air-conditioning system at extreme temperatures. The method according to this paragraph is optionally herein referred to as "heat transfer method 3D" for convenience.

[0065] The present invention also provides a composition that is non-flammable, low-toxic or substantially non-toxic, has a low global warming potential, and has excellent heat transfer performance, particularly in medium-temperature refrigeration systems and methods, and more preferably in defrosting and low-frost medium-temperature refrigeration systems.

[0066] Medium-temperature refrigeration systems and methods are also provided by the present invention as described in detail below.

[0067] Furthermore, the applicants will come to understand that in many evaporators such as direct expansion evaporators, there is a pressure loss when the refrigerant moves through the evaporator, and in many cases, that pressure drop is an amount that results in a saturation temperature drop of about 1°C to 2°C.

[0068] Accordingly, the refrigerant of the present invention has a GWP of greater than about 75 and less than about 150, is classified by ASHRAE as A1 (non-flammable and low toxicity), and includes a refrigerant having an evaporator glide of less than about 3°C, more preferably less than about 2°C, and is preferably used in a system containing an evaporator. The pressure on the refrigerant decreases from the inlet to the outlet of the evaporator in an amount that reduces the saturation temperature of the refrigerant by about 1°C to about 3°C, most preferably about 1°C to about 2°C. This means that the refrigerant of the present invention according to such embodiments can achieve an unexpectedly small change in refrigerant temperature through the evaporator. For example, the change in refrigerant temperature between the inlet and outlet of the evaporator as a result of pressure loss is preferably less than the evaporator gradient (measured at a substantially constant evaporator inlet pressure), and even more preferably less than about 75% of the evaporator gradient, and even more preferably less than about 50% of the evaporator gradient. Accordingly, such a preferred refrigerant composition of the present invention having a GWP of greater than about 75 and less than about 150 and classified by ASHRAE as A1 (non-flammable and low toxicity) is such that when the refrigerant moves through the evaporator, the temperature of the refrigerant can change by an amount of less than about 1°C (i.e., the change in refrigerant temperature between the inlet and outlet of the evaporator as a result of pressure loss is preferably less than about 1°C). As a result of this discovery, at least in part, the methods and systems of the present invention can be achieved using a high-efficiency heat exchanger design, particularly for applications such as reversible heat pumps where the refrigerant flow changes direction in a heat exchanger depending on the operating (cooling or heating) mode.

Brief Description of the Drawings

[0069]

Figure 1A

Figure 1B

Figure 2

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Figure 4

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Figure 5B

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Figure 7

Figure 8

Figure 9

Figure 10

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Figure 12

Mode for Carrying Out the Invention

[0070] Description of Preferred Compositions Definition: As used herein, the terms "low stage" and "high stage" are used in a relative context to designate the relative evaporation temperatures of two or more cascade refrigeration circuits. Thus, the term "low stage" in the context of a cascade refrigeration system refers to a refrigeration circuit in which the refrigerant evaporates at a temperature lower than the evaporation temperature of the refrigerant in the "high stage".

[0071] As used herein, the term "cascade refrigeration" refers to a refrigeration system in which low stage refrigerant vapor is cooled and preferably condensed, at least in part, by rejecting heat to a high stage refrigerant.

[0072] The term "coefficient of performance" (hereinafter "COP") is a widely accepted measure of refrigerant performance that is particularly useful for representing the relative thermodynamic efficiency of a refrigerant in a specific heating or cooling cycle involving evaporation or condensation of the refrigerant. In refrigeration engineering, this term represents the ratio of useful refrigeration or cooling capacity to the energy applied by a compressor during compression of the vapor, and thus represents the ability of a given compressor to pump heat for a given volumetric flow rate of a heat transfer fluid such as a refrigerant. In other words, considering a specific compressor, a refrigerant with a higher COP will supply more cooling or heating power. One means for estimating the COP of a refrigerant under specific operating conditions is from the thermodynamic properties of the refrigerant using standard refrigeration cycle analysis techniques (see, for example, R.C. Downing, FLUOROCARBON REFRIGERANTS HANDBOOK, Chapter 3, Prentice-Hall, 1988, which is incorporated herein by reference in its entirety).

[0073] The term "global warming potential" (hereinafter "GWP") was developed to enable comparison of the effects of various gases on global warming. This compares the amount of heat trapped by a given mass of a gas over a specific time period to the amount of heat trapped by the same mass of carbon dioxide. Carbon dioxide was chosen as the reference gas by the Intergovernmental Panel on Climate Change (IPCC) for climate change, and its GWP is set to 1. The higher the GWP, the more a given gas will warm the Earth over that period compared to CO2. As used herein, the term GWP means the value of GWP measured in accordance with the IPCC Fifth Assessment Report, 2014 1 and is referred to herein as AR5 and abbreviated.

[0074] 1Myhre, G., D. Shindell, F.-M. Breon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change[Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. https: / / www.ipcc.ch / pdf / assessmentreport / ar5 / wg1 / WG1AR5_Chapter08_FINAL.pdf (p. 73-79)

[0075] The term "non-flammable" refers to a compound or composition that is determined to be non-flammable when judged under the conditions described in ASTM Standard E-681-2009 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases), ASHRAE Standard 34-2016 Designation and Safety Classification of Refrigerants, and Appendix B1 of ASHRAE Standard 34-2016 (each standard as it exists at the filing date of this application), which are hereby incorporated by reference in their entirety (the "non-flammability test"). Flammability is defined as the ability of a composition to ignite and / or spread flame. Under this test, flammability is judged by measuring the flame angle. Non-flammable substances are classified as Class "1" by ASHRAE Standard 34-2016 Designation and Safety Classification of Refrigerants (each standard as it exists at the filing date of this application).

[0076] As used herein, the term "evaporator glide" means the difference between the saturation temperature of the refrigerant at the inlet of the evaporator and the dew point of the refrigerant at the outlet of the evaporator, assuming that the pressure at the outlet of the evaporator is the same as the pressure at the inlet. As used herein, the phrase "saturation temperature" means the temperature at which a liquid refrigerant boils to become vapor at a given pressure.

[0077] As used herein, the phrase "non-toxic or low toxicity" means that the composition is classified as Class "A" by ASHRAE Standard 34-2016 Designation and Safety Classification of Refrigerants and is described in Appendix B1 of ASHRAE Standard 34-2016 (since each standard existed as of the filing date of this application). Substances that are non-flammable and of low toxicity are classified as "A1" by ASHRAE Standard 34-2016 Designation and Safety Classification of Refrigerants and are described in Appendix B1 of ASHRAE Standard 34-2016 (as each standard existed as of the filing date of this application).

[0078] The term "superheat" or simply "superheated" means the temperature rise of the refrigerant at the outlet of the evaporator above the saturated vapor temperature (or dew point temperature) of the refrigerant.

[0079] As used herein, the term "E-1,3,3,3-tetrafluoropropene" means the trans isomer of HFO-1234ze and is abbreviated as HFO-1234ze(E).

[0080] As used herein, the term "E-1,1,1,4,4,4-hexafluorobut-2-ene" means the trans isomer of HFO-1336mzz and is abbreviated as HFO-1336mzz(E).

[0081] As used herein, the term "1,1,1,2,3,3,3-heptafluoropropane" is abbreviated as HFC-227ea.

[0082] As used herein, the term "low-temperature refrigeration" refers to a refrigeration system that operates under the following conditions: (a) a condenser temperature of about 15°C to about 50°C and (b) an evaporator temperature of about -40°C to about -15°C or below within that range.

[0083] As used herein, the term "medium-temperature refrigeration" refers to a refrigeration system that utilizes one or more compressors and operates under the following conditions: (a) a condenser temperature of about 15°C to about 60°C and (b) an evaporator temperature of about -15°C to about 5°C or within that range.

[0084] As used herein, the term "extreme temperature air conditioning system" means a vapor compression air conditioning system in which the condensation temperature of the refrigerant is about 55°C to about 95°C.

[0085] As used herein, the term "high-temperature heat pump system" means a vapor compression system operable in heating mode in which the condensation temperature of the refrigerant is about 55°C to about 95°C.

[0086] As used herein, the term "R454C" means a refrigerant designated as 454C by ASHRAE and consisting of 21.5% +2 / -2% R-32 and 78.5 -+2 / -2% HFC-1234yf.

[0087] As used herein, the term "R455A" means a refrigerant designated as 455AC by ASHRAE and consisting of 21.5% +2 / -1% R-32, 75.5 HFC-1234yf +2 / -2%, and 3% +2 / -1% CO2.

[0088] As used herein, the term "R471A" means a refrigerant designated as 471A by ASHRAE and consisting of 78.7% +0.4 / -1.5% HFC-1234ze(E), 17% +1.5 / -0.4% HFC-1336mzz(E), and 4.3% +1.5 / -0.4% HFC-227ea.

[0089] As used herein, the term "R476A" means a refrigerant specified as 476A by ASHRAE and consisting of 78.7% + / - 0.5 / -2% of HFC-1234ze(E), 12% +2 / -0.5% of HFC-1336mzz(E), and 10% +2 / -0.51% of HFC-134a.

[0090] As used herein, the term "about" with respect to an amount expressed in weight percent means that the amount of the component can vary by an amount of + / - 2 weight %.

[0091] Cascade system The present invention includes a cascade refrigeration system including each of Systems 1-7, wherein the inter-circuit heat exchanger is a flooded heat exchanger in which the high-stage refrigerant evaporates in the heat exchanger by absorbing heat from the low-stage refrigerant. As used herein, a reference to a numbered system or group of numbered systems defined herein means each of such numbered systems, including each system having a number within the group and including any numbered system with a suffix. For example, a reference to System 1 includes a reference to each of Systems 1A, 1B, and 1C.

[0092] As used herein, the term "flooded heat exchanger" refers to a heat exchanger that evaporates a liquid refrigerant to produce refrigerant vapor without substantially any superheat. As used herein, the term "without substantially any superheat" means that the vapor exiting the evaporator is at a temperature not exceeding 1°C above the boiling temperature of the liquid refrigerant in the heat exchanger.

[0093] The present invention also includes a cascade refrigeration system including each of Systems 1-7, wherein the low-stage refrigeration circuit includes one or more, preferably a plurality of, low-temperature refrigeration circuits.

[0094] The present invention also includes a cascade refrigeration system including each of Systems 1-7, wherein the low-stage refrigeration circuit includes one or more, preferably a plurality of, low-temperature refrigeration circuits, and the high-stage refrigeration circuit includes one or more intermediate-temperature refrigerant circuits.

[0095] In a preferred embodiment included in each of Systems 1 to 7, the high-stage refrigeration circuit is disposed substantially entirely outside the low-stage refrigeration unit. As used herein, the term "substantially entirely outside" means that, except for transport piping and the like that can be considered part of the high-stage circuit to provide heat exchange between the low-stage refrigerant and the high-stage refrigerant via an inter-circuit heat exchanger, which can pass through the low-stage circuit or be disposed near or between the low-stage circuits, the high-stage components are generally disposed away from the corresponding components of the low-stage refrigeration unit.

[0096] In a preferred embodiment included in each of Systems 1 to 7, the low-stage circuit includes one or more "refrigeration units", preferably "low-temperature refrigeration units". As used herein, the term "refrigeration unit" means a structure that is at least partially enclosed and / or completely closable and can provide cooling inside at least a part of the structure, and is structurally distinct from any structure that surrounds or contains the high-stage circuit.

[0097] In a preferred embodiment included in each of Systems 1 to 7, the high-stage circuit includes one or more "refrigeration units", preferably "medium-temperature refrigeration units".

[0098] The high-stage circuit in the cascade system of the present invention included in each of Systems 1 to 7 may further include a fluid receiver for receiving the high-stage refrigerant from the condenser in the high-stage circuit.

[0099] Each refrigeration unit included in each of Systems 1 to 7 can be disposed in a first area. The first area may be a shop floor. This means that each first refrigeration circuit (preferably a low-temperature refrigeration circuit) may also be disposed in the first area such as a shop floor.

[0100] Each refrigeration unit included in each of Systems 1 to 7 may include a space and / or an object contained within the space to be cooled. Preferably, the space is inside the refrigeration unit. Each evaporator in the lower stage of such a preferred refrigeration unit may be arranged to cool its respective space / object, preferably by cooling the air within the space to be cooled.

[0101] As described above, the high-stage refrigeration circuit of the present invention included in each of Systems 1 to 7 may have components extending between a first lower-stage circuit (preferably a low-temperature refrigeration unit) and at least a second region remote from the lower-stage circuit, preferably when the high-stage circuit includes an intermediate-temperature refrigeration circuit. The second region may be, for example, a machine room that houses a substantial portion of the components of the high-stage circuit.

[0102] The high-stage refrigeration circuit (preferably including an intermediate-temperature refrigeration circuit) of the present invention including each of Systems 1 to 7 may extend to the second and third regions. The third region may be an area outside the building or group of buildings in which the lower-stage circuit is located. This enables the use of ambient cooling.

[0103] Unless otherwise indicated herein for a particular embodiment, the refrigerant in the high-stage circuit may be non-flammable and classified as A1 under ASHRAE 34 (measured by ASTM E681) or classified as A2L under ASHRAE 34 (measured by ASTM E681). This may be desirable when the high-stage refrigeration circuit includes long piping extending between different areas of a building, such as between a shop floor (where low-stage refrigeration units may be deployed) and a machine room. Thus, having a flammable refrigerant in the high-stage refrigeration circuit can be dangerous because the high-stage circuit extends over a larger area and thus exposes more people and / or structures to the risk of fire, increasing both the risk of leakage and the potential severity of a leak.

[0104] Each of the low-stage refrigeration circuits included in each of Systems 1 to 7 may include at least one fluid expansion device. The at least one fluid expansion device may be a capillary tube or an orifice tube. This means that simpler flow control devices, such as capillary tubes and orifice tubes, can be advantageously used, and preferably are advantageously used, in the low-stage refrigeration circuits of the present invention including each of Systems 1 to 7.

[0105] An embodiment of a cascade refrigeration system according to the present invention is schematically illustrated in FIG. 2 and will be described in detail below.

[0106] FIG. 2 shows a cascade refrigeration system 200. More specifically, FIG. 2 shows a refrigeration system 200 having three low-stage refrigeration circuits 220a, 220b, and 220c. Each of the low-stage refrigeration circuits 220a, 220b, 220c has an evaporator 223, a compressor 221, a heat exchanger 230, and an expansion valve 222. Each of the compressor, evaporator, and heat exchanger in the circuit is illustrated by a single icon, but it will be understood that the compressor, evaporator, heat exchanger, expansion valve, etc. may each include a plurality of such units. In each of the circuits 220a, 220b, and 220c, the evaporator 223, the compressor 221, the heat exchanger 230, and the expansion valve 222 are connected in series with each other in the listed order. Each of the low-stage refrigeration circuits 220a, 220b, and 220c is included inside a separate respective refrigeration unit (not shown). In this example, each of the three refrigeration units is preferably a refrigerator unit, and the refrigerator units house the respective low-temperature refrigeration circuits. In this way, each refrigeration unit includes a dedicated built-in low-temperature refrigeration circuit. The refrigeration units (not shown), and thus the low-temperature refrigeration circuits 220a, 220b, 220c, may be disposed, for example, on the sales floor 242 of a supermarket.

[0107] In this example, the refrigerant in each of the low-stage refrigeration circuits 220a, 220b, and 220c is a low-GWP refrigerant such as CO2, propane, HFO-1234yf, R454C, R455A, or a combination of two or more of these. As will be understood by those skilled in the art, the refrigerant in each of the low-stage circuits 220a, 220b, and 220c may be the same as or different from the refrigerant in the other low-stage refrigeration circuits 220a, 220b, and 220c. However, in a preferred embodiment, each of the plurality of low-stage circuits contains CO2, propane, HFO-1234yf, R454C, R455A, or a combination of two or more of these.

[0108] The refrigeration system 200 also has a high-stage refrigeration circuit 210. The high-stage circuit 210 has a compressor 211, a condenser 213, and a fluid receiver 214. The compressor 211, the condenser 213, and the fluid receiver 214 are connected in series in a given order. Each of the compressor, condenser, fluid receiver, etc. in the high-stage circuit is illustrated by a single icon, but it will be understood that the compressor, evaporator, heat exchanger, expansion valve, etc. may each include a plurality of such units. The high-stage refrigeration circuit 210 also has four parallel-connected branches, namely, three medium-temperature cooling branches 217a, 217b, and 217c that are not in heat transfer communication with the low stage, and a low-stage cooling branch 216. The four parallel-connected branches 217a, 217b, 217c, and 216 are connected between the fluid receiver 214 and the compressor 211. Each of the medium-temperature cooling branches 217a, 217b, and 217c has an expansion valve 218a, 218b, and 218c, and an evaporator 219a, 219b, and 219c, respectively. The expansion valve 218 and the evaporator 219 are connected in series in a given order between the fluid receiver 214 and the condenser 211. In a preferred embodiment, the high-stage circuit 220 including the low-temperature cooling branch 216 has an expansion valve 212 and an interface in the form of inlet and outlet pipes, conduits, valves, etc. (collectively represented as 260a, 260b, and 260c, respectively), which supply high-stage refrigerant liquid to each of the inter-circuit heat exchangers 230a, 230b, 230c disposed within the refrigeration unit 220 and bring high-stage refrigerant vapor from each of the inter-circuit heat exchangers 230a, 230b, 230c, as shown in the preferred embodiment. The low-temperature cooling branch 216 connects each of the inter-circuit heat exchangers 230a, 230b, 230c at their respective circuit interface positions 231a, 231b, 231c. Each of the circuit interface positions 231a, 231b, 231c is arranged in a series-parallel combination with each of the other circuit interface positions 231a, 231b, 231c.

[0109] The high-stage refrigeration circuit 210 has components that extend between the sales floor 242, the machine room 241, and the roof 140. The cooling branch 216 and the medium-temperature branches 218a, 218b, 218c of the medium-temperature refrigeration circuit 210 are preferably disposed on the sales floor 242. The compressor 211 and the fluid receiver 214 are preferably disposed within the machine room 241. The condenser 213 is preferably disposed in a location where it can be easily exposed to ambient conditions, such as on the roof 240.

[0110] In this example, the refrigerant within the high-stage refrigeration circuit 210 comprises at least about 75 weight % HFO-1234ze and comprises, consists essentially of, or consists of a refrigerant having a flammability of class A1 or A2L. The present invention includes a cascade system in which the refrigerant within the high-stage refrigeration circuit 210 comprises, consists essentially of, or consists of HFO-1234ze(E), R471A, and / or R476A. More advantageously, the blend has a low GWP, as illustrated in the examples herein, making it an environmentally considerate solution and having excellent heat transfer performance characteristics.

[0111] The use of the preferred embodiment illustrated in FIG. 2 can be summarized as follows: · Each of the low-stage refrigeration circuits 220a, 220b, 220c absorbs heat via their evaporators 223 to provide low-temperature cooling to a space (not shown) to be cooled; · The high-stage refrigeration circuit 210 absorbs heat from each of the inter-circuit heat exchangers 230a, 230b, 230c via branch 216 to cool and condense the low-stage refrigerant vapor from each of the respective compressors in the low-stage circuits 220a, 220b, 220c; · The high-stage refrigeration circuit 210 absorbs heat in each of the evaporators 219 to provide medium-temperature cooling to a space (not shown) to be cooled; and · Heat is removed from the refrigerant in the high-stage refrigeration circuit 210 within the air-cooled chiller 213.

[0112] Using the configuration of the invention of the type shown in FIG. 2, in particular, since each refrigeration circuit 230 is built into its respective refrigeration unit, several beneficial results can be achieved.

[0113] For example, the installation and removal of the refrigeration unit and the overall cascade refrigeration system 200 are simplified. This is because a refrigeration unit having built-in refrigeration circuits 220a, 220b, 220c can be easily connected or disconnected from the high-stage refrigeration circuit 210 without the need for modifications to the refrigeration circuits 220, 220b, 220c. In other words, the refrigeration unit can be simply "plugged in and out" with respect to the high-stage refrigeration circuit 210.

[0114] Another advantage is that each refrigeration unit can be subjected to a default factory test before being installed in the live refrigeration system 200, including its corresponding first refrigeration circuits 220a, 220b, 220c. This reduces the possibility of defects that may include potentially harmful refrigerant leaks. Therefore, a reduced leak rate can be achieved.

[0115] Another advantage in the preferred embodiment is the provision of a flooded circuit-to-circuit heat exchanger in the system of the invention, including each of systems 1-7, which provides improved heat transfer between the low stage and the high stage. Therefore, the efficiency of the overall refrigeration system is improved.

[0116] In a preferred embodiment including each of Systems 1-7, the present invention also includes a cascade refrigeration system, the cascade refrigeration system including a plurality of low-temperature refrigeration circuits, each low-temperature refrigeration circuit including a low-temperature refrigerant having a GWP of about 150 or less and including at least about 50 wt%, or at least about 75 wt%, of R1234yf, such as specifically R-454C and / or R455A; a compressor having a work output of about 3.5 kilowatts or less; an inter-circuit heat exchanger in which the low-temperature refrigerant condenses in a temperature range from about -5°C to about -15°C; a medium-temperature refrigeration circuit containing a medium-temperature refrigerant, the medium-temperature refrigerant including at least about 75 wt% of HFO-1234ze(E), such as specifically R471A and / or R476A, consisting essentially of these, or consisting of these; and an evaporator in which the medium-temperature refrigerant evaporates at a temperature in the range of about -5°C to about -15°C, which is less than the condensation temperature of the low-temperature refrigerant, and in which the medium-temperature refrigerant absorbs heat from the low-temperature refrigerant in the heat exchanger and thereby evaporates.

[0117] In a preferred embodiment including each of Systems 1-7, the present invention also includes a cascade refrigeration system, the cascade refrigeration system including a plurality of low-temperature refrigeration circuits, each low-temperature refrigeration circuit including a low-temperature refrigerant having a GWP of about 150 or less and including at least about 50 wt%, or at least about 75 wt%, of R1234yf, such as specifically R-454C and R-455A; a compressor having a compression rating of 2 horsepower or less; an inter-circuit heat exchanger in which the low-temperature refrigerant condenses in a temperature range from about -5°C to about -15°C; a medium-temperature refrigeration circuit containing a medium-temperature refrigerant, the medium-temperature refrigerant including at least about 75 wt% of HFO-1234ze(E), such as specifically R471A and / or R476A, consisting essentially of these, or consisting of these; and an evaporator in which the medium-temperature refrigerant evaporates at a temperature in the range of about -5°C to about -15°C, which is less than the condensation temperature of the low-temperature refrigerant, and in which the medium-temperature refrigerant absorbs heat from the low-temperature refrigerant in the heat exchanger and thereby evaporates.

[0118] Cascade Refrigeration System - Alternative According to the present invention, including each of systems 1 to 7, as would be understood by one of ordinary skill in the art considering the teachings contained herein, any number of low-stage refrigeration circuits 220 may be present. In particular, there may be the same number of low-stage circuits 220 as the number of refrigeration units to be cooled. Thus, the high-stage refrigeration circuit 210 may interact with any number of low-stage refrigeration circuits 220, and vice versa.

[0119] As would be apparent to one of ordinary skill in the art considering the teachings contained herein, according to the present invention, including each of systems 1 to 4, any number and configuration of high-stage circuit branches 217 and evaporators 218 may be present. In an alternative configuration according to the present invention, including each of systems 1 to 7, each low-stage circuit 220 may be arranged completely in parallel with the other low-stage circuits 220. An example of such a configuration is shown in FIG. 3. FIG. 3 shows a system 300 in which each circuit interface position is present within inter-circuit heat exchangers 231a, 231b, 231c where the circuit interface positions of each other are arranged completely in parallel. The components of system 300 are the same as those of system 200 in other respects (described with reference to FIG. 2), and the components of system 300 function in substantially the same manner as system 200, provided that it will be understood that the overall system performance and other important features of the overall system may be significantly affected by this configuration change.

[0120] Helpfully, this means that only a given portion of the refrigerant from the high-stage circuit 210 passes through one inter-circuit heat exchanger 230 before returning to the compressor 211. Thus, this configuration, as in the case of the series configuration, does not allow any heat exchanger to receive a portion of the refrigerant preheated as a result of passing through the upstream heat exchanger, ensuring that each of the heat exchangers 230 receives the high-stage refrigerant at approximately the same temperature.

[0121] As would be apparent to one of ordinary skill in the art considering the teachings contained herein, many other configurations of the circuit interface positions 231a, 231b, 231c for one high-stage refrigeration circuit 210 according to the present invention, including each of systems 1 to 7, can be achieved and are actually envisioned.

[0122] In view of the teachings contained herein, the preferred module design of the low-stage circuits of the preferred embodiments of the present invention, each including systems 1-7, enables the use of a non-flammable low-pressure refrigerant having a relatively low GWP.

[0123] Cascade refrigeration system having a flooded evaporator A preferred refrigeration system of the present invention is illustrated and described herein with reference to FIG. 4, which schematically shows a cascade refrigeration system 400 having a high-stage refrigeration circuit 410 with a receiver 414 for delivering liquid refrigerant that provides flooded evaporator operation in an inter-circuit heat exchanger 431. More specifically, FIG. 4 shows a refrigeration system 400 having two low-stage refrigeration circuits 420a, 420b. Each of the low-stage refrigeration circuits 420a, 420b has an evaporator 423, a compressor 421, an inter-circuit heat exchanger 431, and an expansion valve 422. In each circuit 420a, 420b, the evaporator 423, the compressor 421, the heat exchanger 430, and the expansion valve 422 are connected in series with each other in the recited order. Each of the first refrigeration circuits 420a, 420b is preferably provided within its respective refrigeration unit (not shown). In a preferred embodiment, each low-stage refrigeration circuit is contained within a refrigerator unit, and the refrigerator unit houses its respective low-stage refrigeration circuit. In this way, a dedicated built-in refrigeration circuit is provided for each refrigeration unit. The refrigeration units (not shown), and thus the low-stage refrigeration circuits 420a, 420b, are preferably disposed on the sales floor 462 of a supermarket in a preferred embodiment.

[0124] The receiver 414 is arranged to separate the gaseous and liquid refrigerants after they have passed through the expansion valve 418, and thus to pass them to the medium-temperature cooling branch 417 and the low-temperature cooling branch 416 - and thus to pass them to the evaporator 419 and the heat exchangers 430a, 430b - the refrigerant that can pass is essentially 100% liquid. Another key feature of the refrigeration system 400 is the pump 442. The pump 442 drives the refrigerant into the medium-temperature branch 417 and the low-temperature branch 416. In an alternative system configuration, the concentration difference between the liquid and vapor phases of the refrigerant drives the system and does not require any pump or blower.

[0125] In this example, the low-stage refrigerant in the refrigeration circuits 420a and 420b contains, consists essentially of, or consists of a low-GWP non-flammable (class A1) refrigerant that contains at least about 50 wt% or at least about 75 wt% of R1234yf (specifically including R-454C and / or R455A). As will be understood by those skilled in the art, the refrigerant in each of the refrigeration circuits 420a, 420b may be the same as or different from the refrigerant in the other of the first refrigeration circuits 420a, 420b.

[0126] The refrigeration system 400 also has a high-stage refrigeration circuit 410 having a compressor branch 450 and a peripheral cooling branch 451. The compressor branch 450 is connected in parallel with the peripheral cooling branch 451. The compressor branch 450 has a compressor 411, a condenser 413, an expansion valve 418, and a receiver 414. The compressor 411, the condenser 413, and the expansion valve 418 are connected in series in a given order. The receiver 414 is connected between the compressor 411 inlet and the expansion valve 418 outlet. The peripheral cooling branch 451 has a chiller 452.

[0127] The compressor branch 450 and the ambient cooling branch 451 are connected in parallel by a first controllable valve 440 and a second controllable valve 441. The controllable valves 440, 441 are controllable such that they can control the amount of refrigerant flowing through each of the compressor branch 450 and the ambient cooling branch 451. The first control valve 440 is connected in series with a pump 442.

[0128] The high-stage refrigeration circuit 410 also has two further branches connected in parallel with each other, namely an intermediate-temperature cooling branch 417 that supplies liquid refrigerant to the inter-circuit heat exchanger 431 and a low-temperature cooling branch 416.

[0129] The intermediate-temperature cooling branch 417 and the branch 416 are connected between the pump 442 and the second controllable valve 441. The intermediate-temperature cooling branch 417 has an evaporator 419. The low-temperature cooling branch 416 connects the inter-circuit heat exchangers 430a, 430b of the first refrigeration circuits 420a, 420b at respective circuit interface positions 431a, 431b. Each of the circuit interface positions 431a, 431b is a combination of in-line and parallel with the other circuit interface positions 431a, 431b.

[0130] The cascade system 400 includes components that extend the high-stage and low-stage circuits between the sales floor 462, the machine room 461, and the roof 440. The branch 416 that carries the high-stage liquid refrigerant to the inter-circuit heat exchanger and the intermediate-temperature cooling branch 417 are preferably each disposed mainly on the sales floor 462. Disposed mainly on the sales floor 462 means that the circuit positions 431a, 431b and the evaporator 419 are disposed on or very close to the sales floor 462. However, the junctions between the low-temperature cooling branch 416 and the intermediate-temperature cooling branch 417 and a part of the pipes of the low-temperature branch 416 and the intermediate-temperature branch 417 can be disposed within the machine room 461.

[0131] In a preferred embodiment, the compressor branch 450 includes components that extend the branch between the machine room 461 and the roof 460. More specifically, the compressor 411, the expansion valve 418, and the flooded receiver 414 are preferably arranged within the machine room 461. The condenser 413 is preferably arranged in a location where easy access to the ambient air is possible, such as on the roof 460.

[0132] The ambient cooling branch 450 preferably includes components that extend the branch between the machine room 461 and the roof 460. The chiller 452 is also arranged in a location where easy access to the ambient air is possible, such as on the roof 603.

[0133] The first controllable valve 440 and the second controllable valve 441 are preferably arranged within the machine room 461. The pump 442 is preferably arranged within the machine room 442.

[0134] In this example, the refrigerant in the high-stage circuit 410 preferably contains, consists essentially of, or consists of at least about 75 wt% of HFO-1234ze(E) (especially including R471A).

[0135] Structurally different, during use, the refrigeration system 400 operates in a manner similar to the refrigeration system 200 with the following key differences. First, the receivers in the high-stage refrigeration circuit 410 within the refrigeration system 400 result in the inter-circuit heat exchangers 430a and 430b being flooded evaporators for the high-stage circuit, and the medium-temperature evaporator 419 is also a flooded evaporator.

[0136] Those skilled in the art will understand, based on the disclosure and teachings contained herein, that there are various advantages associated with using the refrigeration configuration according to the present invention, including each of the cascade systems 1 - 7 that use a flooded evaporator as disclosed, for example, in system 400.

[0137] The Applicants have found that one such advantage is an unexpected improvement in the coefficient of performance (COP). Without necessarily being bound by any particular theory, this unexpected advantage is thought to arise in part from the fact that the compressor 411 requires less work and the system enables an operation involving superheating of the refrigerant before it enters the compressor, which improves the cooling capacity of the second refrigeration circuit 410.

[0138] A second difference is that, compared to the refrigeration system 200, the way in which the refrigeration system 400 operates is to provide an ambient cooling branch 451 and controllable valves 440, 441. The ambient cooling branch 451 enables bypassing of the compressor branch 450 and cooling of the refrigerant when the ambient temperature is low enough. This is achieved by routing the ambient cooling branch 451 to the roof 460 to provide maximum exposure of the refrigerant to the ambient air temperature. This is sometimes referred to as winter operation. Helpfully, this provides that it essentially does not involve cooling of the refrigerant in the second refrigeration circuit 410. Clearly, this is advantageous from a cost and environmental perspective as the energy consumption is significantly reduced compared to operating the compressor branch 450.

[0139] For convenience purposes, terms such as "flooded system", "flooded cascade system", etc. refer to the systems of the present disclosure where at least one, preferably all, of the heat exchangers in the low-stage refrigeration circuit (preferably the low-temperature circuit) for condensing the low-stage refrigerant (preferably the medium-temperature refrigerant) are flooded evaporators for the high-stage refrigerant (preferably the medium-temperature refrigerant). In the preferred embodiments according to the present invention, each of Systems 1-7, the medium-temperature evaporator is also a flooded evaporator. The potential advantages described with respect to the cascade refrigeration system apply equally well to the flooded cascade refrigeration system, and the terms used to describe the flooded refrigeration system and the non-flooded cascade refrigeration system are equivalent.

[0140] Further advantages of the flooded cascade refrigeration system according to the present invention, including each of systems 1 to 7, include reduction of energy consumption due to utilization of the ambient cooling branch (winter operation), improvement of heat transfer performance due to flooded operation of the heat exchanger and evaporator, elimination of the need for a temperature control expansion valve by providing a pump in the circuit, and the ability to use low-cost materials for manufacturing it due to its suitability for the low-pressure refrigerant of the second refrigeration circuit.

[0141] In particular, considering the advantages described herein, the present invention, including each of systems 1 to 7, includes a cascade refrigeration system, which includes a plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit including a low-GWP, non-flammable (class A1) refrigerant containing at least about 50 wt% or at least about 75 wt% of R1234yf, for example specifically R-454C and / or R455A, consisting essentially of or consisting of these; a low-stage refrigeration circuit; a compressor having a horsepower rating of about 2 hp or less; an inter-circuit heat exchanger where the low-stage refrigerant condenses; a high-stage refrigeration circuit containing a high-stage refrigerant, the high-stage refrigerant containing at least about 75 wt% of HFO-1234ze(E), for example particularly R471A and / or R476A, consisting essentially of or consisting of these; and a flooded evaporator where the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the first refrigerant at a temperature below the condensation temperature of the low-stage refrigerant.

[0142] Flooded cascade refrigeration system - alternatives Regarding the cascade refrigeration system, the above alternatives are equally applicable to the flooded cascade refrigeration system. Other alternatives include removal of the ambient cooling branch 451 and / or conversion of the flooded system to a direct expansion system. Further modifications of system 400 are envisioned where the ambient cooling branch, including each of systems 1 to 7, bypasses only the compressor 411 rather than the entire compressor branch, and the ambient cooling branch can be short and simplified.

[0143] Advantageously, by using shortened ambient cooling branches, i.e., the branches convey liquid refrigerant from the receiver outlet to the condenser inlet, firstly, the circuit is simplified because a chiller and a first controllable valve are no longer required at the inlet of the receiver pump, and secondly, the amount of extra piping and the number of components for the ambient cooling branches are reduced, thus resulting in a lower-cost circuit due to reduced material costs.

[0144] Suction line heat exchanger Any further possible modification of the systems forming part of the present disclosure, including each of systems 1 - 7, is that any number of built-in refrigeration circuits may include a suction line heat exchanger (SLHX). More specifically, any of the low-stage refrigeration circuits 220a, 220b, 220c within system 200, including each of systems 1 - 7, may include an SLHX, and any of the low-stage refrigeration circuits 420a, 420b may include an SLHX. For comparison, FIG. 5A shows a refrigeration circuit 700 without an SLHX, while FIG. 5B shows a refrigeration circuit 750 with an SLHX 760.

[0145] The circuit 700 of FIG. 5A has a compressor 710, a heat exchanger 720, an expansion valve 730, and an evaporator 740. The compressor 710, the heat exchanger 720, the expansion valve 730, and the evaporator 740 are connected in series in the order listed. In use, the refrigeration circuit 700 functions as described above.

[0146] The circuit 750 of FIG. 5B has the same components as the circuit 700, but an additional SLHX 760 is added. The SLHX provides a heat exchange interface between the line connecting the evaporator 740 and the compressor 710 and the line connecting the heat exchanger 720 and the expansion valve 730. In other words, the SLHX 760 is positioned between the line connecting the evaporator 740 and the compressor 710 (referred to herein as the vapor line) and the line connecting the heat exchanger 720 and the expansion valve 730 (referred to herein as the liquid line). In use, the SLHX transfers heat from the liquid line after the heat exchanger 720 to the vapor line after the evaporator 740. This has two effects, namely, first, an improvement in the efficiency of the circuit 700, and second, a reduction in the efficiency of the circuit 700. First, advantageously, on the liquid line side - i.e., the high pressure side - the subcooling of the liquid refrigerant increases. This is because the extra heat is discharged to the liquid expansion side, which reduces the temperature of the refrigerant entering the expansion valve 730. This additional subcooling leads to a lower inlet quality in the evaporator 740 after the expansion valve 730. This increases the enthalpy difference, thus improving the ability of the refrigerant to absorb heat in the stages of the evaporator 740. Therefore, the performance of the evaporator 740 is improved.

[0147] Second, disadvantageously, on the vapor line side - i.e., the low pressure side - the refrigerant exiting the evaporator 740 receives extra heat from the liquid line, which substantially increases the superheat. This results in a higher suction line temperature. As a result of the higher suction line temperature to the compressor 710, the enthalpy difference in the compression process increases. This increases the power of the compressor required to compress the refrigerant. Therefore, this has an adverse effect on the performance of the system.

[0148] In summary, to determine whether introducing SLHX results in an overall beneficial effect, it is necessary to consider both the first and second effects of improved evaporator capacity and the power requirements of the improved compressor. Generally, the use of SLHX according to the present invention, including each of Systems 1-7, particularly Systems 200 and 300 as described herein, results in an overall positive and unexpectedly beneficial effect.

[0149] Each of the high-stage refrigeration circuits included in each of Systems 1-4 may include a second evaporator. The second evaporator may be connected in parallel with the circuit interface position.

[0150] Each of the circuit interface positions included in each of Systems 1-4 may be connected to each other in a series-parallel combination of the circuit interface positions. Advantageously, this means that when a defect or blockage is detected in one of the circuit interface positions, the first refrigeration circuit, or the first refrigeration unit, the defective position, circuit, or unit can be isolated and / or bypassed by the second refrigeration circuit so that the defect does not spread within the system.

[0151] Each of the circuit interface positions included in each of Systems 1-7 may be connected in series with at least one other circuit interface position.

[0152] Each of the circuit interface positions included in each of Systems 1-7 may be connected in series with each other as circuit interface positions.

[0153] Each of the circuit interface positions included in each of Systems 1-7 may be connected in parallel with at least one other circuit interface position.

[0154] Each of the circuit interface positions included in each of Systems 1-7 may be connected in parallel with each other as circuit interface positions.

[0155] Refrigerant composition HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea The present invention provides a refrigerant that may comprise, consist essentially of, or consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea, and such a refrigerant is particularly useful as a high-stage refrigerant in the preferred cascade systems of the present invention, including in particular Systems 1-7.

[0156] The present invention also provides a refrigerant that may comprise, consist essentially of, or consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea, and such a refrigerant is particularly useful in heat transfer methods, including in particular Heat Transfer Method Systems 1-3.

[0157] The refrigerant may comprise (a) from about 74.6% to about 78.6% by weight of HFO-1234ze(E), (b) from about 17% to about 21% by weight of HFO-1336mzz(E), and (c) greater than 0% to about 4.4% by weight of HFC-227ea. Preferably, the refrigerant comprises (a) from 74.6% to about 78.6% by weight of HFO-1234ze(E), (b) from about 17% to about 19% by weight of HFO-1336mzz(E), and (c) about 4.4% by weight of HFC-227ea. For example, the refrigerant may comprise HFC-227ea in an amount of about 4.4% by weight. It will be understood that the refrigerant may consist essentially of or consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the amounts described above. The refrigerant described in this paragraph is optionally referred to herein as "Refrigerant 1A" for convenience.

[0158] The refrigerant may include (a) about 78.6% by weight of HFO-1234ze(E), (b) about 17% by weight of HFO-1336mzz(E), and (c) about 4.4% by weight of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the amounts described above, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph may optionally be referred to as "Refrigerant 1B" for convenience.

[0159] The refrigerant may include (a) about 76.6% by weight of HFO-1234ze(E), (b) about 19% by weight of HFO-1336mzz(E), and (c) about 4.4% by weight of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the amounts described above, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph may optionally be referred to as "Refrigerant 1C" for convenience.

[0160] The refrigerant may include (a) about 74.6% by weight of HFO-1234ze(E), (b) about 21% by weight of HFO-1336mzz(E), and (c) about 4.4% by weight of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the amounts described above, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph may optionally be referred to as "Refrigerant 1D" for convenience.

[0161] The refrigerant may include (a) about 78.6 wt% + 0.5 wt% / -2.0 wt% of HFO-1234ze(E), (b) 17 wt% + 2.0 wt% / -0.5 wt% of HFO-1336mzz(E), and (c) 4.4 wt% + 2.0 wt% / -0.5 wt% of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the above amounts, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph is optionally referred to as "Refrigerant 1E" for convenience.

[0162] The refrigerant may include (a) about 76.6 wt% + 0.5 wt% / -2.0 wt% of HFO-1234ze(E), (b) 19 wt% + 2.0 wt% / -0.5 wt% of HFO-1336mzz(E), and (c) 4.4 wt% + 2.0 wt% / -0.5 wt% of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the above amounts, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph is optionally referred to as "Refrigerant 1F" for convenience.

[0163] The refrigerant may include (a) about 74.6 wt% + 0.5 wt% / -2.0 wt% of HFO-1234ze(E), (b) 21 wt% + 2.0 wt% / -0.5 wt% of HFO-1336mzz(E), and (c) 4.4 wt% + 2.0 wt% / -0.5 wt% of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the above amounts, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph is optionally referred to as "Refrigerant 1G" for convenience.

[0164] The refrigerant may contain (a) 78.6% by weight of HFO-1234ze(E), (b) 17% by weight of HFO-1336mzz(E), and (c) 4.4% by weight of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the above amounts, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph may optionally be referred to as "Refrigerant 1H" for convenience.

[0165] The refrigerant may contain (a) 76.6% by weight of HFO-1234ze(E), (b) 19% by weight of HFO-1336mzz(E), and (c) 4.4% by weight of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the above amounts, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph may optionally be referred to as "Refrigerant 1I" for convenience.

[0166] The refrigerant may contain (a) 74.6% by weight of HFO-1234ze(E), (b) 21% by weight of HFO-1336mzz(E), and (c) 4.4% by weight of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the above amounts, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph may optionally be referred to as "Refrigerant 1J" for convenience.

[0167] The refrigerant may include: (a) from about 78.6 wt% to about 80.6 wt% of HFO-1234ze(E); (b) from about 15 wt% to about 17 wt% of HFO-1336mzz(E); and (c) about 4.4 wt% of HFC-227ea. It will be understood that the refrigerant may consist essentially of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea in the amounts described above, or may consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant described in this paragraph is sometimes referred to as "Refrigerant 1K" for convenience.

[0168] Refrigerants containing each of Refrigerants 1A - 1K have a GWP of less than about 150. As used herein, the term "Refrigerants 1A - 1K" means each of Refrigerants 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, and 1K, separately and independently. Refrigerants containing each of Refrigerants 1A - 1K are non-toxic or have low toxicity. That is, the refrigerant is a Class A refrigerant.

[0169] Refrigerants containing each of Refrigerants 1A - 1K preferably have a glide of less than 4.5, more preferably less than about 3°C, and even more preferably less than about 2°C.

[0170] It will be understood that refrigerants containing each of Refrigerants 1A - 1I in preferred embodiments have one or more, and most preferably all combinations, of the above characteristics.

[0171] Heat transfer composition: The refrigerant of the present invention can be provided in a heat transfer composition.

[0172] The heat transfer composition of the present invention can include any of the preferred refrigerant compositions disclosed herein, and in particular the refrigerant of the present invention containing each of Refrigerants 1A - 1K. The heat transfer composition described in this paragraph is sometimes referred to as "Heat Transfer Composition 1" for convenience.

[0173] The present invention also relates to a heat transfer composition comprising a refrigerant containing each of refrigerants 1A to 1K in an amount of at least about 80% by weight, or at least about 90% by weight, or at least about 97% by weight, or at least about 99% by weight of the heat transfer composition. The heat transfer composition described in this paragraph may optionally be referred to as heat transfer composition 2 for convenience.

[0174] The heat transfer composition can consist essentially of or consist of the refrigerant. The heat transfer composition described in this paragraph may optionally be referred to as heat transfer composition 3 for convenience.

[0175] Lubricant: Preferably, the heat transfer composition may further comprise a lubricant. The lubricant lubricates the refrigerant compressor using the refrigerant. Preferably, the lubricant is present in the heat transfer composition in an amount of about 1% to about 50% by weight, more preferably in an amount of about 10% to about 50% by weight, and most preferably in an amount of about 30% to about 50% by weight of the heat transfer composition. Useful lubricants include alkylbenzenes, esters, polyol esters ("POE"), polyalkylene glycols ("PAG"), polyvinyl ethers ("PVE"), poly(alpha-olefins) ("PAO"), and combinations thereof. A commercially available alkylbenzene lubricant is Zerol 150 (registered trademark). PAG is available as GM Goodwrench Refrigeration Oil and MOPAR-56. Other useful esters include phosphate esters, dibasic acid esters, and fluoroesters.

[0176] Commercially available POEs include neopentyl glycol dipermalonic acid available as Emery 2917 (registered trademark) and Hatcol 2370 (registered trademark), and pentaerythritol derivatives such as those sold under the trade names Emkarate RL32 - 3MAF and Emkarate RL68H by CPI Fluid Engineering. Emkarate RL32 - 3MAF and Emkarate RL68H have the properties identified in the following table:

[0177]

Table 1

[0178] Commercially available PVEs include polyvinyl ether FVC - 32D (registered trademark) and FVC - 68D (registered trademark) by Idemitsu.

[0179] Preferred lubricants include POE and PVE, more preferably POE. Of course, different mixtures of different types of lubricants may be used.

[0180] The heat transfer composition of the present invention can essentially consist of, or consist of, a refrigerant containing each of refrigerants 1A - 1K and a lubricant containing each of the preferred lubricants as described above. The heat transfer composition described in this paragraph is optionally referred to as "heat transfer composition 4" for convenience.

[0181] A preferred heat transfer composition of the invention contains any one of refrigerants 1A - 1K and a POE lubricant. The heat transfer composition described in this paragraph is optionally referred to as "heat transfer composition 5" for convenience.

[0182] A preferred heat transfer composition of the invention contains any one of refrigerants 1A - 1K and a PAG lubricant. The heat transfer composition described in this paragraph is optionally referred to as "heat transfer composition 6" for convenience.

[0183] A preferred heat transfer composition of the invention comprises any one of refrigerants 1A to 1K and a PVE lubricant. The heat transfer composition described in this paragraph may be referred to as "heat transfer composition 7" for convenience.

[0184] The present invention also includes a high-temperature heat pump system that includes the refrigerant of the present invention containing each of refrigerants 1A to 1K and / or the heat transfer composition of the present invention containing each of heat transfer compositions 1 to 7 and / or operates according to heat transfer methods 1 to 3, and provides specific advantages in relation thereto. The heat transfer system described in this paragraph may be referred to as "heat transfer system 1" for convenience.

[0185] The present invention also includes a two-stage vapor injection compression type medium-temperature refrigeration system that includes the refrigerant of the present invention containing each of refrigerants 1A to 1K and / or the heat transfer composition of the present invention containing each of heat transfer compositions 1 to 7 and / or operates according to heat transfer methods 1 to 3, and provides specific advantages in relation thereto. The heat transfer system described in this paragraph may be referred to as "heat transfer system 2" for convenience.

[0186] The present invention also includes a vending machine that includes the refrigerant of the present invention containing each of refrigerants 1A to 1K and / or the heat transfer composition of the present invention containing each of heat transfer compositions 1 to 7 and / or includes an intake line / liquid line heat exchanger and operates according to heat transfer methods 1 to 3, and provides specific advantages in relation thereto. The heat transfer system described in this paragraph may be referred to as "heat transfer system 3" for convenience.

[0187] The present invention also includes a heat pump type water heater with an intake line / liquid line heat exchanger that includes the refrigerant of the present invention containing each of refrigerants 1A to 1K and / or the heat transfer composition of the present invention containing each of heat transfer compositions 1 to 7 and / or operates according to heat transfer methods 1 to 3, and provides specific advantages in relation thereto. The heat transfer system described in this paragraph may be referred to as "heat transfer system 4" for convenience.

[0188] The present invention also includes an air conditioning system including a mobile, residential, or commercial air conditioning system that contains the refrigerant of the present invention containing each of refrigerants 1A to 1K and / or the heat transfer composition of the present invention containing each of heat transfer compositions 1 to 7 and / or operates according to heat transfer methods 1 to 3, and provides specific advantages in relation thereto. The heat transfer system described in this paragraph is optionally referred to as "heat transfer system 5" for convenience.

[0189] The present invention also includes a secondary fluid refrigeration system that contains the refrigerant of the present invention containing each of refrigerants 1A to 1K and / or the heat transfer composition of the present invention containing each of heat transfer compositions 1 to 7 and / or operates according to heat transfer methods 1 to 3, and provides specific advantages in relation thereto. The heat transfer system described in this paragraph is optionally referred to as "heat transfer system 6" for convenience.

Examples

[0190] In the following examples, the refrigerant composition, which is the subject of one or more of the examples, is identified in the examples. Each refrigerant was subjected to a thermodynamic analysis to determine its ability to match the operating characteristics of R-404A in various refrigeration systems. The analysis was performed using experimental data collected on the properties of various binary and ternary pairs of components used in the refrigerants. In the experimental evaluation, the composition of each set was varied over a series of relative percentages, and the mixing parameters of each set were regressed against the experimentally obtained data. In the examples, known vapor / liquid equilibrium behavior data available in the National Institute of Science and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database software (Refprop 9.1 NIST Standard Database 23 from April 2016) were used. The parameters selected for the analysis were the same compressor volume for all refrigerants, the same operating conditions for all refrigerants, and the same compressor adiabatic and volumetric efficiencies for all refrigerants. In each example, simulations were performed using the measured vapor-liquid equilibrium data. The simulation results are reported for each example.

[0191] Example 1: Performance in a Cascade Refrigeration System Cascade systems are generally used in applications where there is a large temperature difference between the ambient temperature and the temperature in the storage (e.g., about 50 - 80°C, such as about 60 - 70°C) (e.g., the temperature difference between the air side of the condenser in the high stage and the air side of the evaporator in the low stage). For example, a cascade system may be used to freeze products in a supermarket. In the following example, the baseline cascade system uses CO2 in the low stage and R134a in the high stage, and the combinations of refrigerants of the present invention involve the low stage of the cascade refrigeration system being CO2 or propane or HFO-1234yf or R454C or 455A, and the refrigerant used in the high stage of the system being 1234ze(E) or R471A or R476A.

[0192] The operating conditions were as follows: · Condensation temperature = 45 °C · High-stage condensation temperature - Ambient temperature = 10 °C · Subcooling of the high-stage condenser = 0.0 °C (system with a receiver) · Evaporation temperature = -30 °C, corresponding in-box temperature = -18 °C · Low-stage evaporator superheat = 3.3 °C · Adiabatic efficiency of the high-stage and low-stage compressors = 65% · Volumetric efficiency = 100% · Temperature rise in the low-stage of the suction line = 15 °C · Temperature rise in the high-stage of the suction line = 10 °C · CO2 condensation temperature of the intermediate heat exchanger = 0 °C, 5 °C, and 10 °C · Superheat of the intermediate heat exchanger = 3.3 °C · Temperature difference in the intermediate heat exchanger = 8 °C

[0193] Report the results in Table E1 below.

[0194]

Table 2

[0195] As can be seen from the results reported in Table E1 above, in all cases, the refrigerant combinations of the present invention, including those defined in Systems 1-7, resulted in efficiencies that were as high as or higher than the baseline efficiency.

[0196] Example 2: Microcascade Refrigeration System The microcascade system combines a conventional medium-temperature DX refrigeration system, with or without a suction line liquid line heat exchanger (SLHX), which operates with the same refrigerant pair as specified in Table 1 above. As used herein, the term "medium-temperature DX refrigeration system" refers to a medium-temperature system where the evaporator is a dry evaporator.

[0197] Useful microcascade systems are disclosed in U.S. Patent Application No. 16 / 014,863, filed on June 21, 2018, and U.S. Patent Application No. 16 / 015,145, filed on June 21, 2018, which claim priority to U.S. Patent Application No. 62 / 522,386, filed on June 21, 2017, U.S. Patent Application No. 62 / 522,846, filed on June 21, 2017, U.S. Patent Application No. 62 / 522,851, filed on June 21, 2017, and U.S. Patent Application No. 62 / 522,860, filed on June 21, 2017, and the entire disclosures of which are incorporated herein by reference.

[0198] Operating conditions: Baseline R404A combining MT system and LT system · Refrigeration capacity ○ Low temperature: 33,000 W ○ Medium temperature: 67,000 W · Volumetric efficiency: 95% for both MT and LT · Compressor adiabatic efficiency ○ Medium temperature = 70% and low temperature = 67% · Condensing temperature: 105°F · Medium temperature evaporation temperature: 20°F · Low temperature evaporation temperature: -20°F · Evaporator superheat: 10°F (both medium temperature and low temperature) · Suction line temperature rise (due to heat transfer to the surroundings) ○ Baseline: Medium temperature: 25°F, low temperature: 50°F ○ Built-in type without cascade / SLHX: Medium temperature: 10°F, low temperature: 25°F ○ Built-in type with cascade / SLHX: Medium temperature: 10°F, low temperature: 15°F SLHX efficiency during use: 65%

[0199] Report the results in Table E2 below.

[0200]

Table 3

[0201] As can be seen from the results reported in Table E2 above, in all cases, the combinations of refrigerants of the present invention, including those defined by Systems 1-7, achieved efficiencies of about 122% or higher than that of the baseline while achieving equivalent capacity to the baseline. This is an important and unexpected advantage.

[0202] Example 3: Performance in an air conditioning system with extreme temperatures Refrigerant R471A was performance tested in a fixed air conditioning system under various condenser temperature conditions within an extreme temperature range. Using R134a as the baseline refrigerant, an analysis was conducted to evaluate the efficiency of R471A in this system, which generally represents Refrigerants 1A-1K. Based on the following operating conditions, the results are reported in Tables 3A and 3B below. · Condensing temperature = 55°C to 95°C · Condenser subcooling = 5.0°C · Evaporating temperature = 10°C, corresponding indoor temperature = 35°C · Evaporator superheat = 5.0°C · Compressor adiabatic efficiency = 65% · Volumetric efficiency = 100%

[0203] [Table 4]

[0204] R471A shows similar efficiency to R134a over a range of condensing temperatures corresponding to different ambient temperatures within the extreme temperature air conditioning range. In addition, for the case where the condensing temperature is 75°C, additional performance parameters are provided below.

[0205] [Table 5]

[0206] Considering the results reported in this example, this refrigerant exhibits exceptional performance when all relevant performance factors are considered.

[0207] Example 4: Performance in a High-Temperature Heat Pump System Refrigerant R471A was performance-tested in a high-temperature heat pump under various condenser temperature conditions within the range typically seen for high-temperature heat pumps. Using R134a as the baseline refrigerant, an analysis was conducted to evaluate the efficiency of R471A in this system, which generally represents refrigerants 1A - 1K, under the following conditions.

[0208] Operating Conditions: · Condensing temperature = 55°C - 95°C · Condenser subcooling = 5.0°C · Evaporator heat degree = 30°C · Evaporator superheat = 5.0°C · Compressor adiabatic efficiency = 65% · Volumetric efficiency = 100%

[0209] [Table 6]

[0210] Refrigerant R471A shows similar efficiency to R134a over a range of condensing temperatures corresponding to the range typically present in high-temperature heat pump applications, and R471A exhibits exceptional performance when all relevant performance factors are considered.

[0211] Comparative Example 1 - Centralized-Decentralized Direct Expansion Supermarket Refrigeration System A centralized-decentralized supermarket refrigeration system is provided with a process flow illustrated in Figure 10.

[0212] This system operates using refrigerants R404A and R448A under a series of ambient conditions in the range of approximately -13°C to approximately 45°C under the following conditions.

[0213] [Table 7]

[0214] The results of the system operation (using R404A as the baseline of the COP value in the centralized system of Comparative Example 1) are shown in FIG. 7 together with the results from Example 5 below. The results of Example C2C are shown in FIG. 8 together with the results from Example 5C below for equivalent emissions and weighted COP using Designations I and II. The results in FIG. 8 are reported for ambient temperatures reflecting the approximate temperatures during operation in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0215] Comparative Example 2 - Direct Expansion Cascade Supermarket Refrigeration System A direct expansion cascade supermarket refrigeration system is provided by the process flow illustrated in FIG. 11.

[0216] This system operates under the following conditions with three different refrigerants (R134a, R515B, and R471A) on the high side (MT system) and R744 on the low side (LT system) under a series of ambient conditions in the range of approximately -13°C to approximately 45°C.

[0217] [Table 8]

[0218] The results of the system operation (using R404A as the baseline of the COP in the centralized system of Comparative Example 1) are shown in FIG. 7 together with the results from Example 5 below. The results of Example C2C are shown in FIG. 8 together with the results from Example 5C below for equivalent emissions and weighted COP using Designation III. The results in FIG. 8 are reported for ambient temperatures reflecting the approximate temperatures during operation in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0219] Comparative Example 3 - CO2 Booster Supermarket Refrigeration System A CO2 booster system using a parallel compression system and a mechanical subcooler is provided in a supermarket refrigeration system by the process flow illustrated in FIG. 12.

[0220] This system operates under the following conditions, using R744 and a CO2 booster, over a range of ambient conditions from approximately -13°C to approximately 45°C.

[0221]

Table 9

[0222] The results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for the COP value) are shown in Figure 7 together with the results from Example 5 below. The results of Example C3 are shown in Figure 8 together with the results from Example 5C below, with respect to equivalent emissions and weighted COP, using Designation V. Results are reported in Figure 8 for ambient temperatures reflecting the approximate temperatures during operation in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0223] Comparative Example 4 - R290 Water-Cooled Supermarket Refrigeration System An R290 water-cooled supermarket refrigeration system is provided, which operates under the following conditions, using R744 and a CO2 booster, over a range of ambient conditions from approximately -13°C to approximately 45°C.

[0224]

Table 10

[0225] The results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for the COP) are shown in Figure 7 together with the results from Example 5 below. The results of Example C4 are shown in Figure 8 together with the results from Example 5C below, with respect to equivalent emissions and weighted COP, using Designation VI. Results are reported for ambient temperatures reflecting the approximate temperatures during operation in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0226] Example 5: Microcascade Supermarket Refrigeration System The microcascade supermarket refrigeration system by the process flow illustrated in FIG. 6 operates under the following conditions, using R471A on the high side (MT system) and three different refrigerants (R744, R1234yf, and R455A) on the low side (LT system), under a series of ambient conditions in the range of about -13°C to about 45°C.

[0227]

Table 11

[0228] The results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for the COP value) are shown in FIG. 7 together with the results from the above Comparative Examples for three sets of ambient conditions, namely 13°C, 30°C, and 45°C. The first bar in each group represents the 13°C ambient condition, the second bar in each group represents the 30°C ambient condition, and the third bar in each group represents the 45°C ambient condition. These results show that for each of these ambient temperature conditions, the microcascade system of the present invention provides the highest COP among all the tested systems. Similarly, FIG. 9 illustrates that as a function of ambient temperature, the microcascade system of the present invention designated as Example 5C provides dramatically better results than all the tested systems (except the R744 booster system) at ambient temperatures below about 5°C and significantly better results than all the systems including the R744 booster system at temperatures above 5°C. These results are very beneficial and unexpected.

[0229] The results of this example regarding the life cycle performance analysis (equivalent emissions and weighted COP) are shown in FIG. 8 together with the results from the above-specified Comparative Examples. The emission values are calculated as follows: Direct emissions = refrigerant charge (kg) × ((annual leakage × life) + end of life loss) × GWP Indirect emissions = annual energy consumption × life × emission factor

[0230] As can be seen from FIG. 8, the microcascade system of the present invention designated as Example 5C (IV in FIG. 8) results in the highest weighted COP among all the tested systems at each of the illustrated ambient temperature conditions. Further, the microcascade system of the present invention designated as Example 5C (IV in FIG. 8) results in both direct and indirect emissions that are dramatically superior to those of the R404A centralized system, the R448A decentralized system, and the R477 / R471A DX cascade system, even at the lowest ambient conditions shown in FIG. 9, and has the lowest emissions of all the systems at the ambient conditions represented by both Atlanta, USA and Shanghai, China. These results are highly beneficial and unexpected. These results also show that a system using a refrigerant with the lowest GWP does not necessarily result in the lowest emissions. Rather, the overall emissions of a refrigeration system depend on the energy efficiency of the refrigerant or combination of refrigerants within the system, as well as the GWP of the refrigerant within the system.

Claims

1. A cascade refrigeration system, a. A low-stage refrigeration circuit, having a low-stage refrigerant with a GWP of about 150 or less, and including a compressor, the low-stage refrigeration circuit; b. An inter-circuit heat exchanger in which the low-stage refrigerant condenses; c. A high-stage refrigeration circuit including a high-stage refrigerant, the high-stage refrigerant having (i) any of class A1 or class A2L flammability, (ii) evaporating at a temperature below the condensation temperature of the low-stage refrigerant, (iii) containing at least about 77 wt% of HFO-1234ze(E), and the high-stage refrigerant evaporating in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit. A cascade refrigeration system comprising the high-stage refrigeration circuit.

2. The cascade refrigeration system according to claim 1, wherein the high-stage refrigerant has class A1 flammability.

3. The cascade refrigeration system according to claim 1, wherein the high-stage refrigerant contains at least about 75% of HFO-1234ze(E).

4. The cascade refrigeration system according to claim 3, wherein the high-stage refrigerant consists essentially of HFO-1234ze(E).

5. The cascade refrigeration system according to any one of claims 1 to 4, wherein the low-stage refrigerant contains CO2 and / or propane and / or HFO-1234yf and / or R454C and / or R455A.

6. The cascade refrigeration system according to claim 5, wherein the high-stage refrigerant contains R471A and / or R476A.

7. The cascade refrigeration system according to claim 1, wherein the low-stage refrigeration circuit includes a plurality of low-temperature refrigeration circuits.

8. The cascade refrigeration system according to claim 1, wherein the compressor of the low-stage refrigeration circuit includes at least one compressor having a horsepower rating of about 2 horsepower or less. Claim 9 A method for demonstrating cooling in an air conditioning system at extreme temperatures, comprising: a. providing an air conditioning system comprising a compressor, a condenser, an evaporator, and a refrigerant, wherein the refrigerant comprises: i. about 78.7 wt% HFO-1234ze(E); ii. about 4.3 wt% HFC-227ea; and iii. about 17 wt% HFO-1336mzz(E); b. evaporating the refrigerant in the evaporator; c. condensing the refrigerant at a temperature in the range of about 55°C to about 95°C. Claim 10 A method for demonstrating cooling in a high temperature heat pump, comprising: a. providing a heat pump comprising a compressor, a condenser, an evaporator, and a refrigerant, wherein the refrigerant comprises: i. about 78.7 wt% HFO-1234ze(E); ii. about 4.3 wt% HFC-227ea; and iii. about 17 wt% HFO-1336mzz(E); b. evaporating the refrigerant in the evaporator; c. condensing the refrigerant at a temperature in the range of about 55°C to about 95°C.

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