Non-flammable refrigerants with low GWP and systems and methods for providing refrigeration

Abstract

The present invention provides a cascade refrigeration system in which a low stage includes a refrigerant having a GWP of less than 150 and a high stage includes a Class A1 refrigerant or a Class A2L refrigerant and includes at least about 75% by weight of HFO-1234ze (E).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present invention relates to and claims the benefit of priority of 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 in its entirety as if fully set forth below. Technical Field

[0003] The present invention relates to high efficiency, low global warming potential ("low GWP") refrigerants, and to air conditioning and / or refrigeration systems and methods for providing cooling, particularly including cascade refrigeration systems, which are safe and efficient. Background Art

[0004] The refrigeration industry is facing increasing pressure (due to regulatory changes or other reasons) to replace high global warming potential (GWP) refrigerants (such as R134a and R404A) with low GWP refrigerants (such as refrigerants with a GWP below 150). This is particularly important in commercial refrigeration systems that use large amounts of refrigerant.

[0005] One approach in the past has been to use low GWP refrigerants, such as carbon dioxide (R744) and hydrocarbon refrigerants. However, such approaches that have been used to date may suffer from significant safety and financial disadvantages, such as: poor system energy efficiency, resulting in increased operating costs; high system complexity, resulting in high initial system costs; low system maintainability and reliability, resulting in high maintenance costs; and high system flammability. Systems that include highly flammable refrigerants according to existing arrangements are particularly disadvantageous because they can result in poor safety levels; may conflict with regulatory code restrictions; and can increase the liability of refrigeration system operators and manufacturers. Safety is a particular concern considering that many commercial refrigeration applications (such as supermarket refrigerators, freezers, and cold display cases) are accessible to the public and often operate in densely populated spaces.

[0006] Applicants have therefore recognised that the refrigeration industry continues to need safe, robust and sustainable methods to reduce the use of high GWP refrigerants that may be used with existing technologies.

[0007] Figure 1A One such previously used method is shown. Figure 1A A refrigeration system 100 is shown that is commonly used for commercial refrigeration in supermarkets. The system 100 is a direct expansion system that provides both medium and low temperature refrigeration via a medium temperature refrigeration loop 110 and a low temperature refrigeration loop 120 .

[0008] exist Figure 1AIn a typical previous configuration, marked as 100 in FIG. 1 , the medium temperature refrigeration circuit 110 has R134a as its refrigerant. The medium temperature refrigeration circuit 110 provides medium temperature cooling and removes waste heat of the low temperature refrigeration circuit 120 via a heat exchanger 130. The medium temperature refrigeration circuit 110 extends between the top plate 140, the machine room 141 and the sales area 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 area 142. Available, as discussed above, R744 has a low GWP.

[0009] However, although Figure 1A Refrigeration systems of the type disclosed in the specification may be capable of providing good efficiency levels, but the applicant has recognized that systems of this type have at least two major disadvantages: first, such systems use the high GWP refrigerant R134a (R134a has a GWP of approximately 1300); second, although the low temperature portion of such systems uses the low GWP refrigerant R744, this refrigerant exhibits many of the disadvantages described above, including significant safety and financial disadvantages.

[0010] In addition, in certain refrigeration applications, it is necessary to cool products without exposing those products to temperatures below a certain temperature (such as the freezing point of water). For example, in a supermarket environment, it is often disadvantageous to keep certain products at a reduced temperature relative to the environment, but it is disadvantageous to cool the products to below the freezing point of water at the same time, especially because the preferred cooling method includes indirect cooling with humid ambient air. For these applications, it is also disadvantageous to have a refrigerant temperature below the freezing point of water along the evaporator, because they will cause frost accumulation, and therefore require defrosting the equipment. Avoiding frost accumulation is an important aspect in those applications. Similarly, the cooling of beverages (including water, etc.) should also be carried out under conditions that avoid exposing such products to temperatures below the freezing point of water, because it is not desirable to freeze such products when they are sold. For convenience, the applicant refers to such applications, methods and systems as "non-freezing" applications, methods and systems herein.

[0011] Certain single component fluorocarbons, including chlorofluorocarbons ("CFCs"), hydrochlorofluorocarbons ("HCFCs"), and hydrofluoroolefins ("HFOs"), have been 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 surfaces and, therefore, defrosting is not required. In such refrigeration applications, systems and methods, the use of single component fluids has heretofore been considered particularly desirable because the saturation temperature of such fluids does not change as the fluid evaporates at constant pressure. This is highly desirable because it allows a system or method to be designed with a refrigerant temperature along the evaporator that remains substantially constant during the evaporation process and above the freezing temperature of water, assuming little or no pressure drop as the refrigerant flows through the evaporator. In addition, product applications also typically require a small temperature differential between the air and the refrigerant to reduce dehumidification of the air and, subsequently, removal of moisture content and quality loss of the product. In such applications, the requirements for a small temperature differential and avoidance of frost formation, as well as the need for the evaporator to have a certain positive superheat at the outlet, may be important when selecting a particular refrigerant. Superheat at or below zero (i.e., the refrigerant is not overheated) can result in reduced cooling capacity, efficiency, and potential compressor failure. The term "superheat" or simply "superheat" refers to the temperature of the refrigerant at the evaporator outlet rising above the saturated vapor temperature (or dew point temperature) of the refrigerant.

[0012] This is Figure 1B 1, a typical supermarket product cooling case is shown in schematic form. Typically, as shown in FIG. 1, cooled, humidified air is provided to the product display area of ​​the display case by passing air from the outside of the case 102 and recirculated air 104 through the heat exchange surface of the evaporator coil 106, which is arranged in an area within the display case that is usually separated from the product display area (or at least not visible to consumers) but close to the product display area. The evaporator 106 has a single-component refrigerant inlet 108 and a single-component refrigerant outlet 110. A circulating fan 114 is also used. In systems of the above type, it is highly desirable that the cooling space 112 in the refrigeration system has a refrigerant temperature that is always or substantially always above a certain level along the evaporator. For example, in many applications such as refrigeration of products, the minimum discharge (outlet) temperature of the air in the display case is designed to be about 2°C to 3°C in order to provide a safety margin for avoiding having a cooling space or cooling products that are below the freezing point of water. Furthermore, to minimize the removal of moisture from the air and subsequent drying of the product (mass loss), the temperature difference between the air outlet and the refrigerant needs to be small, typically 2° C. to 3° C. Combined with the fact that the evaporator for these applications requires a superheat of about 3° C. to about 5° C., this will impose a constraint on the allowable evaporator glide of the refrigerant so that the evaporation temperature remains above the freezing point of water and so frost does not accumulate.

[0013] Those skilled in the art will appreciate that these two desired results have heretofore been difficult to provide for refrigerants that are multi-component blends of different single component refrigerants.

[0014] Prior to the present invention, as described above, those skilled in the art have primarily used single component refrigerants, such as HFC-134a, in such applications having low temperature sensitivity and have avoided refrigerant blends because blends generally experience significant changes in boiling temperature upon evaporation, which has heretofore been considered a major obstacle to being able to identify blends having the correct balance of properties for use in such systems.

[0015] On the other hand, applicants have recognized that in many applications it is also difficult to identify a single component fluid having a full set of properties that give it a particular advantage in an application of the type described above. For example, in many important applications it is necessary to identify a refrigerant that simultaneously: (1) has a workable glide, i.e., 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., about 3°C ​​to about 5°C; (2) is non-flammable (Class A1) or only slightly flammable (Class A2L); (3) has low or substantially no toxicity; (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 needs 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. Although in many cases the use of a single-component refrigerant can satisfy item (1), item (2) and item (3), those skilled in the art have found that it has been difficult (if not impossible) to date to find most refrigerants and preferably all refrigerants (whether single component or other components) that satisfy not only item (1), item (2) and item (3) but also item (4) to item (5). Here, non-flammable substances will be classified as Class "1" by ASHRAE, and low toxicity substances will be classified as Class "A" by ASHRAE Standard 34-2016. According to ASHRAE Standard 34-2016, non-flammable and low toxicity substances are classified as "A1".

[0016] For example, although HFC-134a has been used in certain non-refrigeration applications to date, it cannot meet, for example, the low GWP requirement (item 5 above) because HFC-134a has a GWP of about 1,300.

[0017] Applicants have proceeded in a manner contrary to accepted thinking and have discovered unexpected and advantageous results. For example, Applicants have discovered, as described in detail below, that particular blends comprising carefully selected combinations of components can have an advantageous but unexpected combination of non-flammability, while having excellent heat transfer properties, low GWP (e.g., a GWP of less than about 150), low or no toxicity, chemical stability, and lubricant compatibility, among other properties. In addition, Applicants have discovered that the refrigerant compositions of the present invention are particularly advantageous for use in medium temperature refrigeration systems, and especially in cascade refrigeration systems and / or medium temperature refrigeration systems where it is desired to maintain the temperature of the cold air above about 0°C and avoid exposing the air to be cooled to temperatures below about 0°C, so as to protect the cooled products from frost and / or prevent frost on the evaporator coils, which in themselves can have a negative impact on the overall efficiency of such systems due to the need for defrosting and / or inconsistent cooling between coils. Summary of the invention

[0018] Applicants have discovered refrigerant compositions, heat transfer compositions containing refrigerants, refrigeration methods and systems (including cascade heat transfer methods and systems), and / or methods and systems for cooling materials with cryogenic limitations (such as the low or non-refrigeration applications described above).

[0019] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0020] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0021] Low-grade refrigerants with a GWP of about 150 or less; and

[0022] compressor;

[0023] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0024] (c) a high-grade refrigeration circuit comprising a high-grade refrigerant which: (i) has a Class A1 or Class A2L flammability; and (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

[0025] For convenience, a system according to this paragraph is sometimes referred to herein as system 1A.

[0026] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0027] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0028] (i) low-grade refrigerants having a GWP of about 150 or less and a Class A1 or A2L flammability; and

[0029] (ii) compressor;

[0030] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0031] (c) a high-grade refrigeration circuit comprising a high-grade refrigerant which: (i) has a Class A1 flammability or a Class A2L flammability; and (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

[0032] For convenience, a system according to this paragraph is sometimes referred to herein as system 1B.

[0033] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0034] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0035] (iii) low-grade refrigerants having a GWP of about 150 or less and a Class A2L flammability or a Class A1 flammability; and

[0036] (iv) compressors;

[0037] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0038] (c) a high-grade refrigeration circuit comprising a high-grade refrigerant which: (i) has a Class A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

[0039] For convenience, a system according to this paragraph is sometimes referred to herein as system 1C.

[0040] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0041] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0042] (i) a low grade refrigerant consisting essentially of propane; and

[0043] (ii) compressor;

[0044] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0045] (c) a high-grade refrigeration circuit comprising a high-grade refrigerant which: (i) has a Class A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

[0046] For convenience, a system according to this paragraph is sometimes referred to herein as system 2A.

[0047] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0048] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0049] (i) a low-grade refrigerant consisting essentially of R454C; and

[0050] (ii) compressor;

[0051] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0052] (c) a high-grade refrigeration circuit comprising a high-grade refrigerant which: (i) has a Class A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

[0053] For convenience, the system according to this paragraph is sometimes referred to herein as system 2B.

[0054] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0055] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0056] (i) a low-grade refrigerant consisting essentially of R455A; and

[0057] (ii) compressor;

[0058] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0059] (c) a high-grade refrigeration circuit comprising a high-grade refrigerant which: (i) has a Class A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

[0060] For convenience, a system according to this paragraph is sometimes referred to herein as system 2C1.

[0061] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0062] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0063] (i) Low-grade refrigerant consisting essentially of R455A;

[0064] (ii) compressor;

[0065] (iii) condenser;

[0066] (iv) an evaporator; and

[0067] (v) a suction 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;

[0068] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0069] (c) a high-grade refrigeration circuit comprising a high-grade refrigerant which: (i) has a Class A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

[0070] For convenience, the system according to this paragraph is sometimes referred to herein as system 2C2.

[0071] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0072] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0073] (i) Low-grade refrigerant consisting essentially of R455A;

[0074] (ii) compressor;

[0075] (iii) condenser;

[0076] (iv) an evaporator; and

[0077] (v) a suction 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;

[0078] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0079] (c) a high-stage refrigeration circuit comprising a high-stage refrigerant consisting essentially of R471A and evaporating at a temperature lower than the condensation temperature of the low-stage refrigerant, wherein the high-stage refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-stage refrigeration circuit.

[0080] For convenience, the system according to this paragraph is sometimes referred to herein as system 2C3.

[0081] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0082] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0083] (i) Low-grade refrigerant consisting essentially of R455A;

[0084] (ii) compressor;

[0085] (iii) condenser;

[0086] (iv) an evaporator; and

[0087] (v) a suction 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;

[0088] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0089] (c) an advanced refrigeration circuit, the advanced refrigeration circuit comprising:

[0090] i. a high-grade refrigerant which (1) has a Class A1 flammability; (2) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (3) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit;

[0091] ii. compressor;

[0092] iii. Condenser;

[0093] iv. evaporator; and

[0094] v. A suction 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.

[0095] For convenience, the system according to this paragraph is sometimes referred to herein as system 2C4.

[0096] The present invention includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0097] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0098] (i) Low-grade refrigerant consisting essentially of R455A;

[0099] (ii) compressor;

[0100] (iii) condenser;

[0101] (iv) an evaporator; and

[0102] (v) a suction 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;

[0103] (b) an inter-circuit heat exchanger in which the low-grade refrigerant is condensed; and

[0104] (c) an advanced refrigeration circuit, the advanced refrigeration circuit comprising:

[0105] i. a high-grade refrigerant consisting essentially of R471A and evaporating at a temperature lower than the condensation temperature of the low-grade refrigerant, wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit;

[0106] ii. compressor;

[0107] iii. Condenser;

[0108] iv. evaporator; and

[0109] v. A suction 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.

[0110] For convenience, the system according to this paragraph is sometimes referred to herein as system 2C5.

[0111] The present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0112] (a) a plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising:

[0113] (i) a low grade refrigerant consisting essentially of propane; and

[0114] (ii) compressor;

[0115] (b) an inter-circuit heat exchanger in which the low-grade refrigerant condenses, preferably at a temperature in the range of about -5°C to about -15°C; and

[0116] (c) a high-grade refrigeration circuit comprising an A1 refrigerant comprising 78 to 79 weight percent HFO-1234ze(E), 16.5 to 17.5 weight percent HFO-1336mzz(E), and 4 to 5 weight percent HFC-227ea, said high-grade refrigerant evaporating at a temperature below the condensation temperature of said low-grade refrigerant, and preferably evaporating in the range of about -5°C to about -15°C, wherein said high-grade refrigerant evaporates in said inter-circuit heat exchanger by absorbing heat from said low-grade refrigerant.

[0117] For convenience, a system according to this paragraph is sometimes referred to herein as system 3A1.

[0118] The present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0119] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0120] (i) a low grade refrigerant consisting essentially of propane; and

[0121] (ii) compressor;

[0122] (b) an inter-circuit heat exchanger in which the low-grade refrigerant condenses, preferably at a temperature in the range of about -5°C to about -15°C; and

[0123] (c) a high-grade refrigeration circuit consisting essentially of R-471A, said high-grade refrigerant evaporating at a temperature below the condensation temperature of said low-grade refrigerant, and preferably evaporating in the range of about -5°C to about -15°C, wherein said high-grade refrigerant evaporates in said inter-circuit heat exchanger by absorbing heat from said low-grade refrigerant.

[0124] For convenience, the system according to this paragraph is sometimes referred to herein as system 3B.

[0125] The present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0126] (a) a low-stage refrigeration circuit, the low-stage refrigeration circuit comprising:

[0127] (i) a low-grade A2L refrigerant comprising 75 to 80 wt% of HFO-1234yf and 21 to 22 wt% of HFC-32; and

[0128] (ii) compressor;

[0129] (b) an inter-circuit heat exchanger in which the low-grade refrigerant condenses, preferably at a temperature in the range of about -5°C to about -15°C; and

[0130] (c) a high-grade refrigeration circuit comprising an A1 refrigerant comprising 78 to 79 weight percent HFO-1234ze(E), 16.5 to 17.5 weight percent HFO-1336mzz(E), and 4 to 5 weight percent HFC-227ea, said high-grade refrigerant evaporating at a temperature below the condensation temperature of said low-grade refrigerant, and preferably evaporating in the range of about -5°C to about -15°C, wherein said high-grade refrigerant evaporates in said inter-circuit heat exchanger by absorbing heat from said low-grade refrigerant.

[0131] For convenience, a system according to this paragraph is sometimes referred to herein as system 4A.

[0132] The present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0133] (a) a plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising:

[0134] (i) a low-grade A2L refrigerant comprising 75 to 80 wt% of HFO-1234yf and 21 to 22 wt% of HFC-32; and

[0135] (ii) compressor;

[0136] (b) an inter-circuit heat exchanger in which the low-grade refrigerant condenses, preferably at a temperature in the range of about -5°C to about -15°C; and

[0137] (c) a high-grade refrigeration circuit consisting essentially of R471A, said high-grade refrigerant evaporating at a temperature below the condensation temperature of said low-grade refrigerant, and preferably evaporating in the range of about -5°C to about -15°C, wherein said high-grade refrigerant evaporates in said inter-circuit heat exchanger by absorbing heat from said low-grade refrigerant.

[0138] For convenience, a system according to this paragraph is sometimes referred to herein as system 4B.

[0139] The present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0140] (a) a plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising:

[0141] (i) a low-grade A2L refrigerant comprising 78 to 79 wt% of HFO-1234yf and 21 to 22 wt% of HFC-32; and

[0142] (ii) compressor;

[0143] (b) an inter-circuit heat exchanger in which the low-grade refrigerant condenses, preferably at a temperature in the range of about -5°C to about -15°C; and

[0144] (c) a high-grade refrigeration circuit comprising an A1 refrigerant comprising 78 to 79 weight percent HFO-1234ze(E), 16.5 to 17.5 weight percent HFO-1336mzz(E), and 4 to 5 weight percent HFC-227ea, said high-grade refrigerant evaporating at a temperature below the condensation temperature of said low-grade refrigerant, and preferably evaporating in the range of about -5°C to about -15°C, wherein said high-grade refrigerant evaporates in said inter-circuit heat exchanger by absorbing heat from said low-grade refrigerant.

[0145] For convenience, a system according to this paragraph is sometimes referred to herein as system 4C.

[0146] The present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0147] (a) a plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising:

[0148] (i) a low-grade refrigerant consisting essentially of R454C; and

[0149] (ii) compressor;

[0150] (b) an inter-circuit heat exchanger in which the low-grade refrigerant condenses, preferably at a temperature in the range of about -5°C to about -15°C; and

[0151] (c) a high-grade refrigeration circuit comprising an A1 refrigerant comprising 78 to 79 weight percent HFO-1234ze(E), 16.5 to 17.5 weight percent HFO-1336mzz(E), and 4 to 5 weight percent HFC-227ea, said high-grade refrigerant evaporating at a temperature below the condensation temperature of said low-grade refrigerant, and preferably evaporating in the range of about -5°C to about -15°C, wherein said high-grade refrigerant evaporates in said inter-circuit heat exchanger by absorbing heat from said low-grade refrigerant.

[0152] For convenience, a system according to this paragraph is sometimes referred to herein as system 4D.

[0153] The present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising:

[0154] (a) a plurality of low-stage refrigeration circuits, each low-stage refrigeration circuit comprising:

[0155] (i) a low-grade refrigerant consisting essentially of R454C; and

[0156] (ii) compressor;

[0157] (b) an inter-circuit heat exchanger in which the low-grade refrigerant condenses, preferably at a temperature in the range of about -5°C to about -15°C; and

[0158] (c) a high-grade refrigeration circuit comprising a refrigerant consisting essentially of R-471A, said high-grade refrigerant evaporating at a temperature below the condensation temperature of said low-grade refrigerant, and preferably evaporating in the range of about -5°C to about -15°C, wherein said high-grade refrigerant evaporates in said inter-circuit heat exchanger by absorbing heat from said low-grade refrigerant.

[0159] For convenience, a system according to this paragraph is sometimes referred to herein as system 4E.

[0160] The present invention includes a cascade refrigeration system (including each of systems 1 to 4) wherein the low-stage refrigeration circuit includes a plurality of low-stage refrigeration circuits. For convenience, the system according to this paragraph is sometimes referred to herein as system 5A.

[0161] The present invention includes a cascade refrigeration system (including each of systems 1 to 4) wherein the low-stage refrigeration circuit is located in an area open to the public. For convenience, the system according to this paragraph is sometimes referred to herein as system 5B.

[0162] The present invention includes a cascade refrigeration system (including each of systems 1 to 4), wherein the low-stage refrigeration circuit includes a plurality of independently packaged low-stage refrigeration circuits, wherein at least two of such low-stage circuits are contained in separate modular refrigeration units, and each of the modular refrigeration units is positioned in a first area open to the public. For convenience, the system according to this paragraph is sometimes referred to herein as system 5C.

[0163] The present invention includes 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. For convenience, the system according to this paragraph is sometimes referred to herein as system 6.

[0164] The present invention includes a cascade refrigeration system (including each of systems 1 to 6) wherein in the inter-circuit heat exchanger, the low-grade refrigerant condenses at a temperature in the range of about -5°C to about -15°C. For convenience, the system according to this paragraph is sometimes referred to herein as system 7.

[0165] The present invention comprises a method of providing heating and / or cooling, the method comprising:

[0166] a. Providing a vapor compression refrigeration system comprising a compressor, a condenser, an evaporator and a refrigerant, wherein the refrigerant comprises:

[0167] i. 65 wt% to less than 85 wt% of HFO-1234ze(E),

[0168] ii. 3.5 wt% to 5.5 wt% HFC-227ea; and

[0169] iii. about 15 wt % to about 22 wt % HFO-1336mzz(E);

[0170] b. evaporating the refrigerant in the evaporator, wherein the glide of the refrigerant in the evaporator is 3°C or less, and wherein the capacity of the refrigerant in the system is at least about 60% of the capacity of R-134a in the system.

[0171] The method according to this paragraph is sometimes referred to herein as Heat Transfer Method 1 for convenience.

[0172] The present invention comprises a method of providing heating and or cooling, the method comprising:

[0173] a. Providing a vapor compression refrigeration system comprising a compressor, a condenser, an evaporator and a refrigerant, the refrigerant comprising:

[0174] i. 75 wt% to less than 85 wt% HFO-1234ze(E),

[0175] ii. 3.5 wt% to 5.5 wt% HFC-227ea; and

[0176] iii. about 15 wt % to about 20 wt % HFO-1336mzz(E);

[0177] b. evaporating the refrigerant in the evaporator, wherein the glide of the refrigerant in the evaporator is 3°C or less, and wherein the capacity of the refrigerant in the system is at least about 60% of the capacity of R-134a in the system.

[0178] The method according to this paragraph is sometimes referred to herein as Heat Transfer Method 2 for convenience.

[0179] The present invention includes a method of providing cooling, the method comprising:

[0180] a. Providing a vapor compression refrigeration system comprising a compressor, a condenser, an evaporator and a refrigerant, wherein the refrigerant comprises:

[0181] i. 65 wt% to less than 85 wt% of HFO-1234ze(E),

[0182] ii. less than 12 wt% HFC-134a; and

[0183] iii. about 10 wt % to about 22 wt % HFO-1336mzz(E);

[0184] b. evaporating the refrigerant in the evaporator,

[0185] Wherein the refrigeration system is selected from a high temperature heat pump system and an extreme temperature air conditioning system. The method according to this paragraph is sometimes referred to herein as Heat Transfer Method 3A for convenience.

[0186] The present invention includes a method of providing cooling, the method comprising:

[0187] a. Providing a vapor compression refrigeration system comprising a compressor, a condenser, an evaporator and a refrigerant, wherein the refrigerant comprises:

[0188] i. about 78.7 wt. % HFO-1234ze (E),

[0189] ii. about 4.3 wt% HFC-227ea; and

[0190] iii. about 17 wt % HFO-1336mzz(E);

[0191] evaporating the refrigerant in the evaporator,

[0192] wherein the refrigeration system is selected from a high temperature heat pump system and an extreme temperature air conditioning system. The method according to this paragraph is sometimes referred to herein as heat transfer method 3B for convenience.

[0193] The present invention includes a method of providing cooling, the method comprising:

[0194] a. Providing a vapor compression refrigeration system comprising a compressor, a condenser, an evaporator and a refrigerant, the refrigerant essentially consisting of:

[0195] i. about 78.7 wt. % HFO-1234ze (E),

[0196] ii. about 4.3 wt% HFC-227ea; and

[0197] iii. about 17 wt % HFO-1336mzz(E); and

[0198] b. evaporating the refrigerant in the evaporator,

[0199] wherein the refrigeration system is selected from a high temperature heat pump system and an extreme temperature air conditioning system. The method according to this paragraph is sometimes referred to herein as heat transfer method 3C for convenience.

[0200] The present invention includes a method of providing cooling, the method comprising:

[0201] a. Provide a vapor compression refrigeration system comprising a compressor, a condenser, an evaporator and a refrigerant, the refrigerant consisting of:

[0202] i. about 78.7 wt.% + 0.4 / -1.5 wt.% HFO-1234ze (E),

[0203] ii. about 4.3 wt% +1.5 / -0.4 wt% HFC-227ea; and

[0204] iii. about 17 wt% +1.5 / -0.4 wt% HFO-1336mzz(E); and

[0205] b. evaporating the refrigerant in the evaporator,

[0206] Wherein the refrigeration system is selected from a high temperature heat pump system and an extreme temperature air conditioning system. The method according to this paragraph is sometimes referred to herein as Heat Transfer Method 3D for convenience.

[0207] The present invention preferably provides compositions having non-flammability, low or no substantial toxicity, low global warming potential, and excellent heat transfer properties, especially in medium temperature refrigeration systems and methods, and even more preferably in frost-free and low-frost medium temperature refrigeration systems.

[0208] The present invention also provides a medium temperature refrigeration system and method, as described in detail below.

[0209] Furthermore, applicants have recognised that in many evaporators, such as direct expansion evaporators, there is a pressure loss as the refrigerant moves through the evaporator and in many cases the amount of pressure drop causes the saturation temperature to drop by approximately 1°C to 2°C.

[0210] Thus, the refrigerants of the present invention include refrigerants having a GWP greater than about 75 and less than about 150, classified by ASHRAE as A1 (non-flammable and low toxicity), and having an evaporator glide of less than about 3°C, and even more preferably less than about 2°C, and are preferably used in a system comprising an evaporator, wherein the pressure on the refrigerant decreases from the inlet to the outlet of the evaporator to reduce the saturation temperature of the refrigerant by an amount of about 1°C to about 3°C, most preferably about 1°C to about 2°C. This means that the refrigerants of the present invention according to such embodiments are capable of achieving unexpectedly small changes in refrigerant temperature through the evaporator. For example, the change in refrigerant temperature between the evaporator inlet and outlet due to pressure loss is preferably less than the evaporator glide (measured at a substantially constant evaporator inlet pressure), and even more preferably less than about 75% of the evaporator glide, and even more preferably less than about 50% of the evaporator glide. Thus, such preferred refrigerant compositions of the present invention have a GWP greater than about 75 and less than about 150, and are classified by ASHRAE as A1 (non-flammable and low toxicity), such that the temperature of the refrigerant can vary by less than about 1°C as the refrigerant travels through the evaporator (i.e., the change in refrigerant temperature between the evaporator inlet and outlet due to pressure losses is preferably less than about 1°C). Due at least in part to this discovery, the methods and systems of the present invention include those that can utilize and implement efficient heat exchanger designs, particularly for applications such as reversible heat pumps, where the refrigerant flow changes direction in the heat exchanger depending on the operating mode (cooling or heating). BRIEF DESCRIPTION OF THE DRAWINGS

[0211] Figure 1A A typical cascade refrigeration system is shown in schematic form.

[0212] Figure 1BA typical supermarket produce cooling cabinet is shown in schematic form.

[0213] Figure 2 A cascade refrigeration system which may be used in accordance with the present invention is shown.

[0214] Figure 3 An alternative cascade refrigeration system that may be used in accordance with the present invention is shown.

[0215] Figure 4 A cascade refrigeration system using a flooded evaporator is shown.

[0216] Figure 5A and Figure 5B Refrigeration systems with and without a suction line heat exchanger are shown.

[0217] Figure 6 The heat transfer system of Example 5 is shown.

[0218] Figure 7 The COP results of Example 5 and Comparative Examples 1 to 4 are shown in the form of graphs.

[0219] Figure 8 The emission and weighted COP results of Example 5 and Comparative Examples 1 to 4 are shown in graphical form.

[0220] Fig. 9 The changes in the system COP of Example 5 and Comparative Examples 1 to 4 depending on the ambient temperature are shown in the form of a graph.

[0221] Fig.10 The centralized distributed direct expansion supermarket refrigeration system as discussed in Comparative Example 1 is represented in schematic form.

[0222] Fig.11 The direct expansion cascade supermarket refrigeration system as discussed in Comparative Example 2 is shown in schematic form.

[0223] Fig.12 The CO2 boosted supermarket refrigeration system as discussed in Comparative Example 1 is shown in schematic form.

[0224] Description of preferred compositions

[0225] definition :

[0226] As used herein, the terms "low stage" and "high stage" are used in a relative context to refer to the relative evaporation temperatures of two or more cascade refrigeration circuits. Thus, in the context of a cascade refrigeration system, the term "low stage" 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".

[0227] As used herein, the term "cascade refrigeration" refers to a refrigeration system having a low-stage refrigerant vapor that is cooled, at least in part, by rejecting heat to a high-stage refrigerant, and preferably condensed.

[0228] The phrase "coefficient of performance" (hereinafter referred to as "COP") is a measure of the performance of a refrigerant that is generally accepted, and 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, the term represents the ratio of the available refrigeration or cooling capacity to the energy applied by the compressor when compressing the vapor, and therefore represents the ability of a given compressor to pump heat for a given volume flow of a heat transfer fluid such as a refrigerant. In other words, given a specific compressor, a refrigerant with a higher COP will deliver more cooling or heating power. A method for estimating the COP of a refrigerant under specific operating conditions is to estimate from the thermodynamic properties of the refrigerant using standard refrigeration cycle analysis techniques (see, for example, RC Downing, "FLUOROCARBON REFRIGERANTS HANDBOOK", Chapter 3, Prentice-Hall, 1988, which is incorporated herein by reference in its entirety).

[0229] The phrase "global warming potential" (hereinafter "GWP") was created to allow comparison of the global warming impact of different gases. It compares the amount of heat trapped by a certain mass of a gas over a specific time period to the amount of heat trapped by a similar mass of carbon dioxide. Carbon dioxide was selected by the Intergovernmental Panel on Climate Change (IPCC) as the reference gas and its GWP was taken to be 1. The greater the GWP, the more a given gas warms the Earth compared to CO2 over that time period. As used herein, the term GWP refers to the global warming potential of a gas according to the 2014 Climate Change Climate Change Index. 1 The GWP value measured in the IPCC Fifth Assessment Report (hereinafter referred to as AR5).

[0230] The term "nonflammable" refers to a compound or composition that is determined to be nonflammable according to ASTM Standard E-681-2009 Standard Test Method for Flammable Concentration Limits of Chemicals (Vapor and Gases) (as various standards existed prior to the filing date of this application) (the entire text of which is incorporated herein by reference ("Nonflammability Test")) under the conditions described in ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification and in Appendix B1 of ASHRAE Standard 34-2016. Flammability is defined as the ability of a composition to ignite and / or propagate a flame. Under this test, flammability is determined by measuring the flame angle. Nonflammable materials are classified as Class "1" by ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification (as various standards existed prior to the filing date of this application).

[0231] As used herein, the term "evaporator glide" refers to the difference between the saturation temperature of the refrigerant at the evaporator inlet and the dew point of the refrigerant at the evaporator outlet, assuming that the pressure at the evaporator outlet is the same as the pressure at the inlet. As used herein, the phrase "saturation temperature" refers to the temperature at which a liquid refrigerant boils into vapor at a given pressure.

[0232] As used herein, the phrase "non-toxic or low toxicity" means that the composition is classified as Class "A" by ASHRAE Standard 34-2016 Nomenclature and Safety Classification of Refrigerants and is described in Appendix Bl of ASHRAE Standard 34-2016 (as various standards existed prior to the filing date of this application).

[0233] Non-flammable and low toxicity materials are classified as "A1" by ASHRAE Standard 34-2016 Nomenclature and Safety Classification of Refrigerants and are described in ASHRAE Standard 34-2016 Appendix B1 (as various standards existed prior to the filing date of this application).

[0234] The term "superheat" or simply "superheat" refers to the temperature of the refrigerant at the evaporator outlet rising above the saturated vapor temperature (or dew point temperature) of the refrigerant.

[0235] As used herein, the term "E-1,3,3,3-tetrafluoropropene" refers to the trans isomer of HFO-1234ze and is abbreviated as HFO-1234ze(E).

[0236] As used herein, the term “E-1,1,1,4,4,4-hexafluorobut-2-ene” refers to the trans isomer of HFO-1336mzz and is abbreviated as HFO-1336mzz(E).

[0237] As used herein, the term "1,1,1,2,3,3,3-heptafluoropropane" is abbreviated as HFC-227ea.

[0238] As used herein, the term "low temperature refrigeration" refers to a refrigeration system operating at or within the following conditions: (a) a condenser temperature of about 15°C to about 50°C; and (b) an evaporating temperature of about -40°C to about -15°C or lower.

[0239] As used herein, the term "medium temperature refrigeration" refers to a refrigeration system utilizing one or more compressors and operating at or within the following conditions: (a) a condenser temperature of about 15°C to about 60°C; and (b) an evaporating temperature of about -15°C to about 5°C.

[0240] As used herein, the term "extreme temperature air conditioning system" refers to a vapor compression air conditioning system in which the condensing temperature of the refrigerant is from about 55°C to about 95°C.

[0241] As used herein, the term "high temperature heat pump system" refers to a vapor compression system that can be operated in a heating mode with a condensing temperature of the refrigerant of about 55°C to about 95°C.

[0242] As used herein, the term "R454C" refers to a refrigerant designated 454C by ASHRAE and which consists of 21.5% + 2 / - 2% R-32 and 78.5- + 2 / - 2% HFC-1234yf.

[0243] As used herein, the term "R455A" refers to a refrigerant designated by ASHRAE as 455AC and which consists of 21.5%+2 / -1% R-32, 75.5% HFC-1234yf+2 / -2% and 3%+2 / -1% CO2.

[0244] As used herein, the term "R471A" refers to a refrigerant designated 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.

[0245] As used herein, the term "R476A" refers to a refrigerant designated 476A by ASHRAE and consisting of 78.7% + / - 0.5 / - 2% HFC-1234ze(E), 12% +2 / - 0.5% HFC-1336mzz(E) and 10% +2 / - 0.51% HFC-134a.

[0246] As used herein, the term "about" in connection with an amount expressed as a weight percent means that the amount of the component may vary by + / - 2 weight percent.

[0247] Cascade system

[0248] The present invention includes a cascade refrigeration system (including each of systems 1 to 7), wherein the inter-circuit heat exchanger is a flooded heat exchanger, wherein the high-grade refrigerant evaporates in the heat exchanger by absorbing heat from the low-temperature refrigerant. As used herein, reference to a numbering system or group of numbering systems defined herein refers to each numbering system in such numbering system, including each system with a number within the group, including any numbering system with a suffix. For example, reference to system 1 includes reference to each of systems 1A, 1B, and 1C.

[0249] As used herein, a "flooded heat exchanger" refers to a heat exchanger in which liquid refrigerant is evaporated to produce refrigerant vapor without substantial superheating. As used herein, "without substantial superheating" means that the vapor leaving the evaporator is at a temperature no more than 1°C above the boiling temperature of the liquid refrigerant in the heat exchanger.

[0250] The present invention also includes a cascade refrigeration system (including each of systems 1 to 7) in which the low-stage refrigeration circuit includes one or more low-temperature refrigeration circuits, and preferably a plurality of low-temperature refrigeration circuits.

[0251] The present invention also includes a cascade refrigeration system (including each of systems 1 to 7), wherein the low-stage refrigeration circuit includes one or more low-temperature refrigeration circuits, preferably multiple low-temperature refrigeration circuits, and wherein the high-stage refrigeration circuit includes one or more medium-temperature refrigerant circuits.

[0252] In a preferred embodiment (including in each of systems 1 to 7), the high-stage refrigeration circuit is substantially completely located outside the low-stage refrigeration unit. As used herein, the term "substantially completely outside" means that the components of the high-stage are generally located away from the components of the low-stage refrigeration unit, except that transfer piping, etc. that can be considered as part of the high-stage circuit may enter the low-stage circuit or be located near or between the low-stage circuits to provide heat exchange between the refrigerant of the low stage and the refrigerant of the high stage via an inter-circuit heat exchanger.

[0253] In a preferred embodiment (including in each of systems 1 to 7), the low-stage circuit includes one or more "refrigeration units", and preferably a "low-temperature refrigeration unit". As used herein, the term "refrigeration unit" refers to an at least partially closed and / or fully enclosed structure that is capable of providing cooling within at least a portion of the structure and is structurally distinct from any structure that closes or contains the high-stage circuit.

[0254] In a preferred embodiment (including in each of systems 1 to 7), the high-level circuit includes one or more "refrigeration units", and preferably "medium temperature refrigeration units".

[0255] The high-stage circuit in the cascade system of the present invention (included in each of the systems 1 to 7) may further include a fluid receiver for receiving the high-stage refrigerant from the condenser in the high-stage circuit.

[0256] Each refrigeration unit (included in each of systems 1 to 7) may be located in a first area. The first area may be a store floor. This means that each first refrigeration circuit (preferably a low temperature refrigeration circuit) may also be located in a first area, such as a store floor.

[0257] Each refrigeration unit (included in each of systems 1 to 7) may include a space and / or object contained within a space to be refrigerated, and preferably the space is within the refrigeration unit. Each evaporator in the lower stage of such a preferred refrigeration unit may be positioned to refrigerate its respective space / object, preferably by cooling the air within the space to be refrigerated.

[0258] As described above, the high-stage refrigeration circuit of the present invention (included in each of systems 1 to 7, and preferably when the high-stage circuit comprises an intermediate temperature refrigeration circuit) can have components extending between a first low-stage circuit (preferably a low-temperature refrigeration unit) and at least a second area away from the low-stage circuit. The second area can be, for example, a machine room that houses most of the components of the high-stage circuit.

[0259] The high-grade refrigeration circuit of the present invention (including each of the systems 1 to 7 (preferably including the medium-temperature refrigeration circuit)) can be extended to the second area and the third area. The third area can be an area outside the building or buildings in which the low-grade circuit is located. This enables ambient cooling to be utilized.

[0260] Unless otherwise indicated herein for a particular embodiment, the refrigerant in the advanced loop may be non-flammable, i.e., classified as A1 under ASHRAE 34 (as measured by ASTM E681) or classified as A2L under ASHRAE 34 (as measured by ASTM E681). This may be desirable in those cases where the advanced loop includes long pipes extending between different areas of a building: for example, between a store floor (where low-stage refrigeration units may be deployed) to a machine room. Thus, having a flammable refrigerant in an advanced refrigeration loop may be unsafe because both the risk of leakage and the severity of potential leakage increases as the advanced loop spans a larger area, thereby exposing more people and / or structures to fire risk.

[0261] Each low-stage refrigeration circuit (including each of the 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 a fixed orifice. This means that simpler flow control devices such as capillary tubes and throttle tubes can and preferably are advantageously used in the low-stage refrigeration circuit of the present invention (including each of the systems 1 to 7).

[0262] One embodiment of the cascade refrigeration system according to the present invention is Figure 2 It is schematically shown in FIG. 1 and described in detail below.

[0263] Figure 2 A cascade refrigeration system 200 is shown. More specifically, Figure 2 A refrigeration system 200 is shown, which has three low-level refrigeration circuits 220a, 220b and 220c. The low-level cold circuits 220a, 220b, 220c each have an evaporator 223, a compressor 221, a heat exchanger 230 and an expansion valve 222. Although each of the compressor, evaporator and heat exchanger in the circuit is illustrated by a single icon, it should be understood that the compressor, evaporator, heat exchanger, expansion valve, etc. can each include a plurality of such units. In each circuit 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 low-level refrigeration circuit in the low-level refrigeration circuit 220a, 220b and 220c is included in an independent corresponding refrigeration unit (not shown). In this example, each refrigeration unit in the three refrigeration units is preferably a refrigerator unit, and the refrigerator unit accommodates a corresponding low-temperature refrigeration circuit. In this way, each refrigeration unit includes an independent set and dedicated low-temperature refrigeration circuit. The refrigeration unit (not shown) and thus the low-temperature refrigeration circuits 220a, 220b, 220c may be arranged, for example, on the sales area 242 of a supermarket.

[0264] In this example, the refrigerant in each of the low-stage refrigeration circuits 220a, 220b, 220c is a low GWP refrigerant, such as CO2, propane, HFO-1234yf, R454C, R455A, or a combination of two or more thereof. The skilled person will appreciate that the refrigerant in each of the low-stage circuits 220a, 220b, 220c may be the same or different from the refrigerant in each of the other low-stage circuits 220a, 220b, 220c, but 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 thereof.

[0265] The refrigeration system 200 also has an advanced refrigeration circuit 210. The advanced 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. Although each of the compressor, the condenser, the fluid receiver, etc. in the advanced circuit is illustrated by a single icon, it should be understood that the compressor, the evaporator, the heat exchanger, the expansion valve, etc. can each include a plurality of such units. The advanced refrigeration circuit 210 also has four parallel branches: three medium-temperature cooling branches 217a, 217b, and 217c, which are not in communication with the low-stage heat transfer; 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 and in a given order between the fluid receiver 214 and the condenser 211. In a preferred embodiment, the high-grade circuit 220 includes a low-temperature cooling branch 216, which has an expansion valve 212 and an interface in the form of inlet and outlet pipes, conduits, valves, etc. (collectively referred to as 260a, 260b and 260c, respectively), which brings the high-grade refrigerant liquid to each of the inter-circuit heat exchangers 230a, 230b, 230c and takes the high-grade refrigerant vapor out therefrom, as shown in the preferred embodiment, the inter-circuit heat exchanger is located in the refrigeration unit 220. The low temperature cooling branch 216 interfaces with each of the inter-circuit heat exchangers 230a, 230b, 230c at a corresponding circuit interface location 231a, 231b, 231c. Each circuit interface location 231a, 231b, 231c is arranged in a series-parallel combination with each other circuit interface location 231a, 231b, 231c.

[0266] The high-grade refrigeration circuit 210 has components extending between the sales area 242, the machine room 241, and the ceiling 140. The cooling branch 216 and the medium-temperature branches 218a, 218b, 218c of the medium-temperature refrigeration circuit 210 are preferably located on the sales area 242. The compressor 211 and the fluid receiver 214 are preferably located in the machine room 241. The condenser 213 is preferably located where it can be easily exposed to environmental conditions, such as on the ceiling 240.

[0267] In this example, the refrigerant in the advanced refrigeration loop 210 comprises, consists essentially of, or consists of a refrigerant comprising at least about 75% by weight HFO-1234ze and having a class A1 or A2L flammability. The present invention includes a cascade system wherein the refrigerant in the advanced refrigeration loop 210 comprises, consists essentially of, or consists of HFO-1234ze(E), R471A, and / or R476A. Further advantageously, the blend has a low GWP, making it an environmentally friendly solution, and has excellent heat transfer performance characteristics, as shown below in its examples.

[0268] like Figure 2 As shown, the use of the preferred embodiment can be summarized as follows:

[0269] Each of the low-stage refrigeration circuits 220a, 220b, 220c absorbs heat via its evaporator 223 to provide low-temperature cooling to a space to be refrigerated (not shown);

[0270] The high-level refrigeration circuit 210 is connected to the inter-circuit heat exchangers 230a, 230b,

[0271] Each inter-circuit heat exchanger in 230c absorbs heat to cool the condensation of low-stage refrigerant vapor from a corresponding compressor in each of the low-stage circuits 220a, 220b, 220c;

[0272] The high-level refrigeration circuit 210 absorbs heat from each of the evaporators 219 to provide medium-temperature cooling to the space to be refrigerated (not shown); and

[0273] • Heat is removed from the refrigerant in the high-stage refrigeration loop 210 in the air-cooled chiller 213 .

[0274] Multiple favorable results can be used Figure 2 An arrangement of the invention of the type shown is achieved, in particular, by independently packaging each refrigeration circuit 230 in the respective refrigeration unit.

[0275] For example, installation and uninstallation of the refrigeration unit and the overall cascade refrigeration system 200 are simplified. This is because the refrigeration unit with its built-in independent set of refrigeration circuits 220a, 220b, 220c can be easily connected or disconnected with the advanced refrigeration circuit 210 without changing the refrigeration circuits 220, 220b, 220c. In other words, the refrigeration unit can be simply "plugged" into or unplugged from the advanced refrigeration circuit 210.

[0276] Another advantage is that each refrigeration unit (including its respective first refrigeration circuit 220a, 220b, 220c) can be factory tested to default values ​​prior to installation in the live refrigeration system 200. This reduces the likelihood of failures (which may include potentially harmful refrigerant leaks). Thus, reduced leakage rates can be achieved.

[0277] Another advantage in the preferred embodiment is that a flooded inter-circuit heat exchanger is provided in the system of the present invention (including each of the systems 1 to 7), so that the heat transfer between the low stage and the high stage is improved. Therefore, the efficiency of the overall refrigeration system is improved.

[0278] In a preferred embodiment (including each of systems 1 to 7), the present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising: a plurality of low-temperature refrigeration circuits, wherein each low-temperature refrigeration circuit comprises a low-temperature refrigerant having a GWP of about 150 or less and comprises at least about 50% by weight, or at least about 75% by weight, of R1234yf (including R-454C and / or R455A), and a compressor having an output power of about 3.5 kW or less; an inter-circuit heat exchanger, wherein the low-temperature refrigerant is heated at a temperature of about -5°C to about -15°C; ℃ condensation; and a medium-temperature refrigeration circuit comprising a medium-temperature refrigerant, wherein the medium-temperature refrigerant includes, essentially consists of, or consists of: at least about 75% by weight of HFO-1234ze(E) (specifically including R471A and / or R476A), and an evaporator, wherein the medium-temperature refrigerant evaporates at a temperature lower than the condensation temperature of the low-temperature refrigerant and evaporates in the range of about -5℃ to about -15℃, wherein the medium-temperature refrigerant evaporates in the heat exchanger by absorbing heat from the low-temperature refrigerant.

[0279] In a preferred embodiment (including each of systems 1 to 7), the present invention also includes a cascade refrigeration system, the cascade refrigeration system comprising: a plurality of low-temperature refrigeration circuits, wherein each low-temperature refrigeration circuit comprises a low-temperature refrigerant having a GWP of about 150 or less and comprises at least about 50 weight %, or at least about 75 weight % of R1234yf (including R-454C and R-455A), and a compressor having a compression power of two horsepower or less; an inter-circuit heat exchanger, wherein the low-temperature refrigerant is heated at a temperature of about -5°C to about -15°C. condensing within a temperature range; and a medium-temperature refrigeration circuit comprising a medium-temperature refrigerant, wherein the medium-temperature refrigerant includes, is essentially composed of, or is composed of: at least about 75% by weight of HFO-1234ze(E) (specifically including R471A and / or R476A), and an evaporator, wherein the medium-temperature refrigerant evaporates at a temperature lower than the condensation temperature of the low-temperature refrigerant and evaporates within a range of about -5°C to about -15°C, wherein the medium-temperature refrigerant evaporates in the heat exchanger by absorbing heat from the low-temperature refrigerant.

[0280] Cascade Refrigeration System - Alternative Solution

[0281] Those skilled in the art will appreciate from the teachings contained herein that any number of low-stage refrigeration circuits 220 may be present in accordance with the present invention (including each of systems 1 to 7). In particular, there may be as many low-stage refrigeration circuits 220 as there are refrigeration units to be cooled. Thus, the high-stage refrigeration circuit 210 may interface with any number of low-stage refrigeration circuits 220, and vice versa.

[0282] It will be apparent to a skilled artisan based on the teachings contained herein that any number and arrangement of high-stage loop branches 217 and evaporators 218 may be present in accordance with the present invention (including each of systems 1 to 4). In an alternative arrangement according to the present invention (including each of systems 1 to 7), each low-stage loop 220 may be arranged in full parallel with each other low-stage loop 220. An example of such an arrangement is shown in Figure 3 middle. Figure 3 A system 300 is shown in which each circuit interface position in the circuit heat exchangers 231a, 231b, 231c is arranged completely in parallel with each other circuit interface position. The components of the system 300 are otherwise similar to those of the system 200 (see Figure 2 3. Description) is the same, and the components of system 300 function in substantially the same manner as system 200, although it should be understood that the performance of the overall system and other important features of the overall system may be significantly affected by this change in arrangement.

[0283] Usefully, this means that a given portion of the refrigerant from the high-level circuit 210 passes through only one inter-circuit heat exchanger 230 before returning to the compressor 211. The arrangement thus ensures that each heat exchanger 230 will receive high-level refrigerant at approximately the same temperature, as the arrangement prevents any heat exchanger from receiving a portion of the refrigerant that has been preheated by passing through an upstream heat exchanger, as would be the case with a series arrangement.

[0284] It will be apparent to those skilled in the art based on the teachings contained herein that a variety of other arrangements of circuit interface locations 231a, 231b, 231c relative to one and higher refrigeration circuits 210 are achievable and practically contemplated in accordance with the present invention (including each of systems 1 through 7).

[0285] It will be apparent to those skilled in the art based on the teachings contained herein that the preferred modular design of the lower circuit (including each of systems 1 to 7) of the preferred embodiments of the present invention allows the use of non-flammable low-pressure refrigerants with relatively low GWP.

[0286] Cascade refrigeration system with flooded evaporator

[0287] Now refer to Figure 4 To illustrate and describe the preferred refrigeration system of the present invention, the figure schematically shows a cascade refrigeration system 400 having an advanced refrigeration circuit 410 with a receiver 414 delivering liquid refrigerant, which results in flooded evaporator operation in the inter-circuit heat exchanger 431. More specifically, Figure 4 A refrigeration system 400 is shown, which has two low-level refrigeration circuits 420a, 420b. Each of the low-level 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 listed order. Each of the first refrigeration circuits 420a, 420b is preferably arranged in a corresponding refrigeration unit (not shown). In a preferred example, each low-level refrigeration circuit is included in a freezer unit, and the freezer unit accommodates its corresponding low-level refrigeration circuit. In this way, an independent set and dedicated refrigeration circuit is provided for each refrigeration unit. In a preferred embodiment, the refrigeration unit (not shown) and therefore the low-level refrigeration circuits 420a, 420b are positioned on the sales area 462 of the supermarket.

[0288] The receiver 414 is arranged to separate the gaseous and liquid refrigerant after passing through the expansion valve 418 so that the refrigerant allowed to pass through the medium temperature cooling branch 417 and the low temperature cooling branch 416 and thus through the evaporator 419 and the heat exchangers 430a, 430b is essentially 100% liquid. Another key feature of the refrigeration system 400 is the pump 442. The pump 442 drives the refrigerant to the medium temperature branch 417 and the low temperature branch 416. In an alternative system arrangement, the density difference between the liquid and gas phases of the refrigerant drives the system, and no pump or fan is required.

[0289] In this example, the low-grade refrigerant in the refrigeration circuits 420a and 420b includes, consists essentially of, or consists of a low GWP non-flammable (Class A1) refrigerant including at least about 50 wt. %, or at least about 75 wt. % R1234yf (specifically including R-454C and / or R455A). The skilled person will appreciate that the refrigerant in each of the refrigeration circuits 420a, 420b may be the same or different from the refrigerant in the other of the first refrigeration circuits 420a, 420b.

[0290] The refrigeration system 400 also has an advanced refrigeration circuit 410, which has a compressor branch 450 and an ambient cooling branch 451. The compressor branch 450 is connected in parallel with the ambient 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 inlet of the compressor 411 and the outlet of the expansion valve 418. The ambient cooling branch 451 has a cooler 452.

[0291] 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 so that the amount of refrigerant flowing in each of the compressor branch 450 and the ambient cooling branch 451 can be controlled. The first control valve 440 is connected in series with a pump 442.

[0292] The high-level refrigeration circuit 410 also has two additional branches connected in parallel to each other: an intermediate-temperature cooling branch 417 and a low-temperature cooling branch 416, which provide liquid refrigerant to the inter-circuit heat exchanger 431. 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 interfaces with each of the inter-circuit heat exchangers 430a, 430b of the first refrigeration circuit 420a, 420b at a corresponding circuit interface position 431a, 431b. Each of the circuit interface positions 431a, 431b is in a series-parallel combination with the other circuit interface positions 431a, 431b.

[0293] The cascade system 400 includes components that extend the high-stage circuit and the low-stage circuit between the sales area 462, the machine room 461 and the top plate 440. The branch 416 that brings the high-stage liquid refrigerant to the inter-circuit heat exchanger and the medium-temperature cooling branch 417 are preferably each mainly located on the sales area 462. The so-called mainly arranged on the sales area 462 means that the circuit positions 431a, 431b and the evaporator 419 are arranged on the sales area 462 or very close to the sales area. However, the joints between the low-temperature cooling branch 416 and the medium-temperature cooling branch 417 and between some pipes of the low-temperature branch 416 and the medium-temperature branch 417 can be located in the machine room 461.

[0294] In a preferred embodiment, the compressor branch 450 includes components that extend the branch between the machine room 461 and the ceiling 460. More specifically, the compressor 411, the expansion valve 418, and the flooded receiver 414 are preferably located in the machine room 461. The condenser 413 is preferably located where it can easily access ambient air, such as on the ceiling 460.

[0295] The ambient cooling branch 450 preferably includes components that extend the branch between the machine room 461 and the ceiling 460. The cooler 452 is also located where ambient air can be easily accessed, such as on the ceiling 603.

[0296] The first controllable valve 440 and the second controllable valve 441 are preferably located in the machine room 461. The pump 442 is preferably located in the machine room 442.

[0297] In this example, the refrigerant in the high-level loop 410 preferably comprises, consists essentially of, or consists of at least about 75 wt. % HFO-1234ze(E), specifically including R471A.

[0298] Although structurally different, in use, refrigeration system 400 operates in a manner similar to refrigeration system 200, but with the following key differences. First, the receiver in the advanced refrigeration circuit 410 in refrigeration system 400 causes the inter-circuit heat exchangers 430a and 430b to be flooded evaporators for the advanced circuit, and the intermediate temperature evaporator 419 is also a flooded evaporator.

[0299] A skilled artisan will appreciate, based on the disclosure and teachings contained herein, that there are several advantages to using a refrigeration arrangement according to the present invention (including each of cascade systems 1 to 7) that uses a flooded evaporator, as disclosed, for example, in system 400.

[0300] Applicants have discovered that one such advantage is an unexpected increase in coefficient of performance (COP). Without being bound by any particular theory, it is believed that this unexpected advantage is due in part to the fact that less compressor 411 work is required and the cooling capacity of the second refrigeration circuit 410 is increased because the system allows the refrigerant to be superheated before entering the compressor.

[0301] A second difference in the manner of operation of refrigeration system 400 compared to refrigeration system 200 is the provision of an ambient cooling branch 451 and controllable valves 440, 441. When the ambient temperature is low enough to cool the refrigerant, the ambient cooling branch 451 allows the compressor branch 450 to be bypassed. This is achieved by leading the ambient cooling branch 451 to the top plate 460 to provide maximum exposure of the refrigerant to the ambient air temperature. This is sometimes referred to as winter operation. In effect, the refrigerant in the second refrigeration circuit 410 provides essentially free cooling. Obviously, this is advantageous from both a cost and environmental perspective because energy consumption is greatly reduced compared to running the compressor branch 450.

[0302] For convenience, the terms "flooded system", "flooded cascade system", etc. refer to the systems of the present disclosure, wherein at least one heat exchanger and preferably all heat exchangers in the low-stage refrigeration circuit (preferably low-temperature circuit) for condensing the low-stage refrigerant (preferably medium-temperature refrigerant) are flooded evaporators for the high-stage refrigerant (preferably medium-temperature refrigerant). In preferred embodiments according to the present invention (including each of systems 1 to 7), the medium-temperature evaporator is also a flooded evaporator. The potential advantages described with reference to the cascade refrigeration system also apply to the flooded cascade refrigeration system: the terms used to describe flooded and non-flooded cascade refrigeration systems are comparable.

[0303] Another advantage of the flooded cascade refrigeration systems according to the present invention (including each of systems 1 to 7) may include: reduced energy consumption due to the use of the ambient cooling branch (winter operation); improved heat transfer performance in the heat exchanger and evaporator due to their flooded operation; no thermostatic expansion valve is required due to the provision of a pump in the circuit; and low-cost materials can be used to manufacture the second refrigeration circuit due to their suitability for low-pressure refrigerants.

[0304] In particular, according to the advantages described herein, the present invention (including each of systems 1 to 7) includes a cascade refrigeration system, the cascade refrigeration system including: a plurality of low-stage refrigeration circuits, wherein each low-stage refrigeration circuit includes a first refrigerant, the first refrigerant including, essentially consisting of, or consisting of: a low GWP non-flammable (Class A1) refrigerant, the low GWP non-flammable refrigerant including at least about 50% by weight, or at least about 75% by weight of R1234yf (specifically including R-454C and / or R455A), having a horsepower rating of about 2 horsepower or less, a pressure a compressor; and an inter-circuit heat exchanger in which the low-grade refrigerant condenses; and a high-grade refrigeration circuit comprising a high-grade refrigerant and a flooded evaporator, the high-grade refrigerant comprising, essentially consisting of, or consisting of at least about 75 weight percent HFO-1234ze(E) (particularly comprising R471A and / or R476A), in which the high-grade refrigerant evaporates at a temperature below the condensation temperature of the low-grade refrigerant, wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the first refrigerant.

[0305] Flooded Cascade Refrigeration System - Alternative Solution

[0306] The alternatives described above with reference to the cascade refrigeration system are equally applicable to the flooded cascade refrigeration system. Other alternatives include removing the ambient cooling branch 451 and / or reversing the flooded system to a direct expansion system. Another variation of the system 400 (including each of the systems 1 to 7) is that the ambient cooling branch 451 can be shortened and simplified so that it only bypasses the compressor 411, rather than the entire compressor branch.

[0307] Advantageously, a shortened ambient cooling branch is used, i.e., one in which the branch leads the liquid refrigerant from the receiver outlet to the condenser inlet, which results in: firstly, a simplified circuit such as a first controllable valve at the cooler and receiver pump inlet is no longer required; and secondly, a lower cost circuit, since the number of additional pipes and the number of components for the ambient cooling branch are reduced, thus reducing material costs.

[0308] Suction line heat exchanger

[0309] Another possible variation of any system forming part of the present disclosure (including each of systems 1 to 7) is that any number of independently packaged refrigeration circuits may include a suction line heat exchanger (SLHX). More specifically, any of the low-stage refrigeration circuits 220a, 220b, 220c in system 200 (including each of systems 1 to 7) may include a SLHX; and any of the low-stage refrigeration circuits 420a, 420b may include a SLHX. For comparison, Figure 5A A refrigeration circuit 700 without SLHX is shown; Figure 5B A refrigeration circuit 750 with a SLHX 760 is shown.

[0310] Figure 5A The circuit 700 in FIG. 7 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.

[0311] Figure 5B The circuit 750 in FIG. 7 has the same components as the circuit 700 , plus an additional SLHX 760 . 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 will have two effects: first, it increases the efficiency of the circuit 700 ; and second, it decreases 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 is increased. This is because the additional heat is rejected to the liquid expansion side, reducing the temperature of the refrigerant entering the expansion valve 730 . This additional subcooling after the expansion valve 730 process results in a lower inlet mass in the evaporator 740. This increases the enthalpy difference and therefore increases the capacity of the refrigerant to absorb heat in the evaporator 740 stage. Thus, the performance of the evaporator 740 is improved.

[0312] Second, disadvantageously, on the vapor line side (i.e., the low pressure side), the refrigerant leaving the evaporator 740 receives additional heat from the liquid line, effectively increasing the superheat. This results in a higher suction line temperature. Due to the higher suction line temperature to the compressor 710, the enthalpy difference of the compression process increases. This increases the compressor power required to compress the refrigerant. Therefore, this has a detrimental effect on system performance.

[0313] In summary, to determine whether the introduction of the SLHX results in an overall beneficial effect, the first effect and the second effect of increasing the evaporator capacity and increasing the compressor power requirement need to be considered. In general, the use of the SLHX according to the present invention (including each of the systems 1 to 7) and in particular such systems 200 and 300 herein, produces an overall positive and unexpected beneficial effect.

[0314] The high-level refrigeration circuit (included in each of systems 1 to 4) may include a second evaporator. The second evaporator may be connected in parallel with the circuit interface location.

[0315] Each of the circuit interface locations (included in each of systems 1 to 4) can be connected in a series-parallel combination with each of the other of the circuit interface locations. In practice, this means that if one circuit interface location, the first refrigeration circuit, or the first refrigeration unit has a detected fault or obstruction, that location, circuit, or unit can be isolated at the time of the fault and / or bypassed via the second refrigeration circuit so that the fault does not propagate through the system.

[0316] Each of the loop interface locations (included in each of systems 1 to 7 ) may be connected in series with at least one other loop interface location.

[0317] Each of the loop interface locations (included in each of systems 1 to 7 ) may be connected in series with each other of the loop interface locations.

[0318] Each of the loop interface locations (included in each of systems 1 to 7 ) may be connected in parallel with at least one other loop interface location.

[0319] Each of the loop interface locations (included in each of systems 1 to 7 ) may be connected in parallel with each other of the loop interface locations.

[0320] Refrigerant composition

[0321] HFO-1234ze(E), HFO-1336mzz(E) and HFC-227ea

[0322] The present invention provides a refrigerant which may include, consist essentially of, or consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea, and such refrigerant is particularly useful as an advanced refrigerant in the preferred cascade system of the present invention (specifically including systems 1 to 7).

[0323] The present invention also provides a refrigerant which may include, consist essentially of, or consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea, and such refrigerant is particularly useful in heat transfer methods (specifically including heat transfer method systems 1 to 3).

[0324] The refrigerant may include: (a) about 74.6 wt % to about 78.6 wt % HFO-1234ze(E); (b) about 17 wt % to about 21 wt % HFO-1336mzz(E); and (c) greater than 0 wt % to about 4.4 wt % HFC-227ea. Preferably, the refrigerant includes: (a) 74.6 wt % to about 78.6 wt % HFO-1234ze(E); (b) about 17 wt % to about 19 wt % HFO-1336mzz(E); and (c) about 4.4 wt % HFC-227ea. For example, the refrigerant may include HFC-227ea in an amount of about 4.4 wt %. It should be understood that the refrigerant may consist essentially of or consist of the above amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1A for convenience.

[0325] The refrigerant may include: (a) about 78.6 weight percent HFO-1234ze(E); (b) about 17 weight percent HFO-1336mzz(E); and (c) about 4.4 weight percent HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the aforementioned amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1B for convenience.

[0326] The refrigerant may include: (a) about 76.6 weight percent HFO-1234ze(E); (b) about 19 weight percent HFO-1336mzz(E); and (c) about 4.4 weight percent HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the aforementioned amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1C for convenience.

[0327] The refrigerant may include: (a) about 74.6 weight percent HFO-1234ze(E); (b) about 21 weight percent HFO-1336mzz(E); and (c) about 4.4 weight percent HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the aforementioned amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant ID for convenience.

[0328] The refrigerant may include: (a) 78.6 wt% + 0.5 wt% / - 2.0 wt% HFO-1234ze (E); (b) 17 wt% + 2.0 wt% / - 0.5 wt% HFO-1336mzz (E); and (c) 4.4 wt% + 2.0 wt% / - 0.5 wt% HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the above amounts of HFO-1234ze (E), HFO-1336mzz (E) and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1E for convenience.

[0329] The refrigerant may include: (a) 76.6 wt% + 0.5 wt% / - 2.0 wt% HFO-1234ze (E); (b) 19 wt% + 2.0 wt% / - 0.5 wt% HFO-1336mzz (E); and (c) 4.4 wt% + 2.0 wt% / - 0.5 wt% HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the above amounts of HFO-1234ze (E), HFO-1336mzz (E) and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1F for convenience.

[0330] The refrigerant may include: (a) 74.6 wt% + 0.5 wt% / - 2.0 wt% HFO-1234ze (E); (b) 21 wt% + 2.0 wt% / - 0.5 wt% HFO-1336mzz (E); and (c) 4.4 wt% + 2.0 wt% / - 0.5 wt% HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the above amounts of HFO-1234ze (E), HFO-1336mzz (E) and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1G for convenience.

[0331] The refrigerant may include: (a) 78.6 weight percent HFO-1234ze(E); (b) 17 weight percent HFO-1336mzz(E); and (c) 4.4 weight percent HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the aforementioned amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1H for convenience.

[0332] The refrigerant may include: (a) 76.6 weight percent HFO-1234ze(E); (b) 19 weight percent HFO-1336mzz(E); and (c) 4.4 weight percent HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the aforementioned amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant II for convenience.

[0333] The refrigerant may include: (a) 74.6 weight percent HFO-1234ze(E); (b) 21 weight percent HFO-1336mzz(E); and (c) 4.4 weight percent HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the aforementioned amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1J for convenience.

[0334] The refrigerant may include: (a) about 78.6 wt % to about 80.6 wt % HFO-1234ze(E); (b) about 15 wt % to about 17 wt % HFO-1336mzz(E); and (c) about 4.4 wt % HFC-227ea. It should be understood that the refrigerant may consist essentially of or consist of the aforementioned amounts of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea. The refrigerant as described in this paragraph is sometimes referred to as Refrigerant 1K for convenience.

[0335] The refrigerant (including each of refrigerants 1A to 1K) has a GWP of less than about 150. As used herein, the term "refrigerant 1A to 1K" refers to each of refrigerants 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, and 1K, respectively and independently. The refrigerant (including each of refrigerants 1A to 1K) has no toxicity or has low toxicity. In other words, the refrigerant is a Class A refrigerant.

[0336] The refrigerant, including each of Refrigerants 1A to 1K, preferably has a glide of less than 4.5, more preferably less than about 3°C, and even more preferably less than about 2°C.

[0337] It should be understood that in preferred embodiments, the refrigerant (including each of Refrigerants 1A to 1I) has one or a combination of the above characteristics, and most preferably has all of the above characteristics.

[0338] Heat transfer compositions

[0339] The refrigerants of the present invention may be provided in the form of heat transfer compositions.

[0340] The heat transfer composition of the present invention may include a refrigerant of the present invention, including any of the preferred refrigerant compositions disclosed herein, and in particular each of Refrigerants 1A to 1K. The heat transfer composition as described in this paragraph is sometimes referred to as Heat Transfer Composition 1 for convenience.

[0341] The present invention also relates to a heat transfer composition comprising a refrigerant (including each of Refrigerants 1A to 1K) in an amount of at least about 80% by weight of the heat transfer composition, or at least about 90% by weight of the heat transfer composition, or at least about 97% by weight of the heat transfer composition, or at least about 99% by weight of the heat transfer composition. The heat transfer composition as described in this paragraph is sometimes referred to as heat transfer composition 2 for convenience.

[0342] The heat transfer composition may consist essentially of, or consist of, the refrigerant.The heat transfer composition as described in this paragraph is sometimes referred to as heat transfer composition 3 for convenience.

[0343] Lubricants

[0344] Preferably, the heat transfer composition may additionally include a lubricant. The lubricant lubricates the refrigeration compressor using the refrigerant. Preferably, the lubricant is present in the heat transfer composition in an amount of about 1% by weight to about 50% by weight of the heat transfer composition, more preferably about 10% by weight to about 50% by weight of the heat transfer composition, and most preferably about 30% by weight to about 50% by weight of the heat transfer composition. Available lubricants include alkylbenzenes, esters, polyol esters ("POE"), polyalkylene glycols ("PAG"), polyvinyl ethers ("PVE"), poly(alpha-olefins) ("PAO") and combinations thereof. Commercially available alkylbenzene lubricants include Zerol 150 (registered trademark). PAG is available as GM Goodwrench Refrigeration Oil and MOPAR-56. Other available esters include phosphate esters, dibasic acid esters and fluoroesters.

[0345] Commercially available POEs include neopentyl glycol dipelargonate, which is available as Emery 2917 (registered trademark) and Hatcol 2370 (registered trademark), and pentaerythritol derivatives, including those sold by CPI Fluid Engineering under the trade names Emkarate RL32-3MAF and Emkarate RL68H. Emkarate RL32-3MAF and Emkarate RL68H have the properties identified in the following table:

[0346] characteristic RL32-3MAF RL68H Viscosity at 40°C (ASTM D445), cSt Approx. 31 Approx. 67 Viscosity at 100°C (ASTM D445), cSt About 5.6 About 9.4 Pour point (ASTM D97), ℃ Approx. -40 Approx. -40

[0347] Commercially available PVEs include polyvinyl ethers FVC-32D (registered trademark) and FVC-68D (registered trademark) from Idemitsu.

[0348] Preferred lubricants include POE and PVE, more preferably POE. Of course, different mixtures of different types of lubricants may be used.

[0349] The heat transfer composition of the present invention may consist essentially of or consist of a refrigerant, including each of Refrigerants 1A to 1K, and a lubricant, including in particular each of the preferred lubricants described above. The heat transfer composition as described in this paragraph is sometimes referred to as heat transfer composition 4 for convenience.

[0350] A preferred heat transfer composition of the present invention comprises any one of Refrigerants 1A to 1K and a POE lubricant. A heat transfer composition as described in this paragraph is sometimes referred to as Heat Transfer Composition 5 for convenience.

[0351] A preferred heat transfer composition of the present invention comprises any one of Refrigerants 1A to 1K and a PAG lubricant. The heat transfer composition as described in this paragraph is sometimes referred to as Heat Transfer Composition 6 for convenience.

[0352] A preferred heat transfer composition of the present invention comprises any one of Refrigerants 1A to 1K and a PVE lubricant. A heat transfer composition as described in this paragraph is sometimes referred to as Heat Transfer Composition 7 for convenience.

[0353] The present invention also includes, and provides certain advantages associated with, a high temperature heat pump system comprising a refrigerant of the present invention (including each of Refrigerants 1A to 1K), and / or comprising a heat transfer composition of the present invention (including each of Heat Transfer Compositions 1 to 7), and / or operating according to Heat Transfer Methods 1 to 3. A heat transfer system as described in this paragraph is sometimes referred to as Heat Transfer System 1 for convenience.

[0354] The present invention also includes and provides specific advantages associated with a medium temperature refrigeration system with two-stage steam injection compression, which includes a refrigerant of the present invention (including each of Refrigerants 1A to 1K), and / or includes a heat transfer composition of the present invention (including each of Heat Transfer Compositions 1 to 7), and / or operates according to Heat Transfer Methods 1 to 3. The heat transfer system as described in this paragraph is sometimes referred to as Heat Transfer System 2 for convenience.

[0355] The present invention also includes and provides certain advantages associated with a vending machine (including a heat exchanger having a suction line / liquid line) comprising a refrigerant of the present invention (including each of Refrigerants 1A to 1K), and / or comprising a heat transfer composition of the present invention (including each of Heat Transfer Compositions 1 to 7), and / or operating according to Heat Transfer Methods 1 to 3. The heat transfer system as described in this paragraph is sometimes referred to as Heat Transfer System 3 for convenience.

[0356] The present invention also includes an air source heat pump water heater (including a heat exchanger with a suction line / liquid line), and provides specific advantages associated therewith, the air source heat pump water heater includes the refrigerant of the present invention (including each of Refrigerants 1A to 1K), and / or includes the heat transfer composition of the present invention (including each of Heat Transfer Compositions 1 to 7), and / or operates according to Heat Transfer Methods 1 to 3. The heat transfer system as described in this paragraph is sometimes referred to as Heat Transfer System 4 for convenience.

[0357] The present invention also includes, and provides particular advantages associated with, air conditioning systems (including mobile, residential and commercial air conditioning systems) that include a refrigerant of the present invention (including each of Refrigerants 1A to 1B), and / or include a heat transfer composition of the present invention (including each of Heat Transfer Compositions 1 to 7), and / or operate according to Heat Transfer Methods 1 to 3. A heat transfer system as described in this paragraph is sometimes referred to as heat transfer system 5 for convenience.

[0358] The present invention also includes, and provides particular advantages associated with, an auxiliary fluid refrigeration system comprising a refrigerant of the present invention (including each of Refrigerants 1A to 1K), and / or comprising a heat transfer composition of the present invention (including each of Heat Transfer Compositions 1 to 7), and / or operating according to Heat Transfer Methods 1 to 3. A heat transfer system as described in this paragraph is sometimes referred to as Heat Transfer System 6 for convenience. Example

[0359] In the following embodiments, the refrigerant composition as the subject of one or more examples is determined in the examples. Each of the refrigerants is subjected to thermodynamic analysis to determine its ability to match the operating characteristics of R-404A in various refrigeration systems. For the characteristics of various binary and ternary component pairs used in refrigerants, the collected experimental data are analyzed. In the experimental evaluation, the composition of each pair changes in a series of relative percentages, and the mixture parameters of each pair are regressed into experimentally obtained data. The known vapor / liquid equilibrium behavior data obtained from the U.S. Institute of Science and Technology (NIST) reference fluid thermodynamics and transport properties database software (Refprop 9.1NIST standard database 23, from April 2016) are used for embodiments. The parameters selected for implementation analysis are: the same compressor displacement for all refrigerants, the same operating conditions for all refrigerants, the same compressor isentropic and volumetric efficiency for all refrigerants. In each embodiment, the simulation is implemented using the measured vapor liquid equilibrium data. The simulation results of each embodiment are reported.

[0360] Example 1: Performance in a cascade refrigeration system

[0361] Cascade systems are typically used in applications where there is a large temperature difference (e.g., about 50°C-80°C, such as about 60°C-70°C) between the ambient temperature and the cabinet temperature (e.g., the temperature difference between the air side of the condenser of the high stage and the air side of the evaporator of the low stage). For example, a cascade system can be used to freeze products in a supermarket. In the following examples, a baseline cascade system uses CO2 in the low stage and R134a in the high stage, and the refrigerant combination of the present invention involves a cascade refrigeration system in which the low stage is CO2 or propane or HFO-1234yf or R454C or 455A, and the refrigerant used in the high stage of the system is 1234ze(E), or R471A, or R476A.

[0362] The operating conditions are:

[0363] Condensation temperature = 45°C

[0364] Advanced condensing temperature - ambient temperature = 10°C

[0365] · High-level condenser subcooling = 0.0°C (system with receiver)

[0366] Evaporation temperature = -30°C, corresponding box temperature = -18°C

[0367] Low-stage evaporator superheat = 3.3°C

[0368] Isentropic efficiency of high and low stage compressors = 65%

[0369] Volumetric efficiency = 100%

[0370] Temperature rise in the lower stage of the suction line = 15°C

[0371] Temperature rise in the suction line at the upper stage = 10°C

[0372] Intermediate heat exchanger CO2 condensation temperature = 0℃, 5℃ and 10℃

[0373] Intermediate heat exchanger superheat = 3.3°C

[0374] Temperature difference in intermediate heat exchanger = 8°C

[0375] The results are reported in Table E1 below.

[0376] Table E1. Performance in cascade refrigeration system

[0377]

[0378]

[0379] As can be seen from the results reported in Table El above, in every case, the refrigerant combinations of the present invention (including as defined in Systems 1 to 7) produced efficiencies that were as high as or higher than the baseline efficiency.

[0380] Example 2: Micro-cascade refrigeration system

[0381] The micro-cascade system incorporates a conventional medium temperature DX refrigeration system (with or without a suction line liquid line heat exchanger (SLHX)) operating with the same refrigerant pairs as identified above in Table 1. As used herein, the term "medium temperature DX refrigeration system" refers to a medium temperature system in which the evaporator is a dry evaporator.

[0382] Useful micro-cascade systems are disclosed in our pending U.S. Serial Nos. 16 / 014,863 filed on June 21, 2018 and 16 / 015,145 filed on June 21, 2018, claiming priority to U.S. Serial Nos. 62 / 522386 filed on June 21, 2017, 62 / 522846 filed on June 21, 2017, 62 / 522851 filed on June 21, 2017, and 62 / 522860 filed on June 21, 2017, all of which are incorporated herein by reference in their entirety.

[0383] Operating conditions:

[0384] Baseline R404A combined with MT and LT systems

[0385] Cooling capacity

[0386] o Low temperature: 33,000W

[0387] oMedium temperature: 67,000W

[0388] Volumetric efficiency: 95% for both MT and LT

[0389] Isentropic efficiency of compressor

[0390] oMedium temperature = 70%, low temperature = 67%

[0391] Condensation temperature: 105°F

[0392] Medium evaporation temperature: 20℉

[0393] Low temperature evaporation temperature: -20℉

[0394] Evaporator superheat: 10℉ (both medium and low temperatures)

[0395] Suction line temperature rise (due to heat transfer to the surrounding environment)

[0396] oBaseline: Medium temperature: 25℉; Low temperature: 50℉

[0397] o Cascade / Separate Set without SLHX: Medium Temp: 10℉; Low Temp: 25℉

[0398] o Cascade / Separate Set with SLHX: Medium Temperature: 10℉; Low Temperature: 15℉ SLHX Efficiency when in use: 65%

[0399] The results are reported in Table E2 below.

[0400] Table E2 - Micro-cascade performance compared to R404A

[0401]

[0402] As can be seen from the results reported in Table E2 above, in each case, the refrigerant combinations of the present invention (including as defined in Systems 1 through 7) produced efficiencies greater than or equal to about 122% of the baseline case while achieving capacities similar to the baseline. This is an important and unexpected advantage.

[0403] Example 3: Performance in an Extreme Temperature Air Conditioning System

[0404] The performance of refrigerant R471A was tested in a stationary air conditioning system at various condenser temperature conditions within extreme temperature ranges. Using R134a as a baseline refrigerant, an analysis was performed to evaluate the efficiency of R471A in this system, which is typically represented by Refrigerant 1A to 1K. The results are reported in Tables 3A and 3B below, based on the following operating conditions:

[0405] Condensation temperature = 55°C to 95°C

[0406] Condenser subcooling = 5.0℃

[0407] Evaporation temperature = 10°C, corresponding to indoor temperature = 35°C

[0408] Evaporator superheat = 5.0℃

[0409] Compressor isentropic efficiency = 65%

[0410] Volumetric efficiency = 100%

[0411] Table 3A. Performance in Extreme Temperature AC Systems

[0412]

[0413] R471A shows similar efficiency to R134a over a condensing temperature range that corresponds to different ambient temperatures within the extreme temperature air conditioning range. In addition, additional performance parameters are provided below for a condensing temperature of 75°C.

[0414] Table 3B. Performance in extreme temperature air conditioning systems

[0415] refrigerant efficiency capacity Evaporator slip, ℃ R134a 100％ 100％ 0 R471A ～100％ 65％ 1.9

[0416] According to the results reported in this example, this refrigerant shows excellent performance when all relevant performance factors are considered.

[0417] Example 4: Performance in a high temperature heat pump system

[0418] The performance of refrigerant R471A was tested in a high temperature heat pump at various condenser temperature conditions within the range typically encountered in high temperature heat pumps. Under the following conditions, using R134a as the baseline refrigerant, an analysis was performed to evaluate the efficiency of R471A in this system, which is typically represented by refrigerant 1A to 1K.

[0419] Operating conditions:

[0420] Condensation temperature = 55°C to 95°C

[0421] Condenser subcooling = 5.0℃

[0422] Evaporation temperature = 30

[0423] Evaporator superheat = 5.0℃

[0424] Compressor isentropic efficiency = 65%

[0425] Volumetric efficiency = 100%

[0426] Table 4. Performance in high temperature heat pump system

[0427]

[0428] Refrigerant R471A shows an efficiency similar to R134a in a condensing temperature range that corresponds to the range typically found in high temperature heat pump applications, wherein R471A shows superior performance when all relevant performance factors are considered.

[0429] Comparative Example 1 - Centralized Distributed Direct Expansion Supermarket Refrigeration System

[0430] according to Fig.10 The process flow shown provides a centralized distributed supermarket refrigeration system.

[0431] The system was operated under the following conditions with R404A and R448A as refrigerants over a range of ambient conditions ranging from about -13°C to about 45°C.

[0432]

[0433]

[0434] The results of the system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for the COP value) are shown together with the results of Example 5 below. Figure 7 The results of Example C2C (and using the designations I and II), in terms of equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 8 The results for ambient temperature are reported in Figure 8 The figure reflects the approximate temperatures for operations in Oslo, Norway, Atlanta, USA, and Shanghai, China.

[0435] Comparative Example 2 - Direct Expansion Cascade Supermarket Refrigeration System

[0436] according to Fig.11 The process flow shown provides a direct expansion cascade supermarket refrigeration system.

[0437] The systems were operated under a range of ambient conditions ranging from about -13°C to about 45°C with three different refrigerants (R134a, R515B and R471A) in the high side (MT system) and R744 in the low side (LT system) under the following conditions.

[0438]

[0439]

[0440] The results of the system operation (using R404A in the centralized system of Comparative Example 1 as the COP baseline) are shown together with the results of Example 5 below. Figure 7 The results of Example C2C (and using the name III), in terms of equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 8 The results for ambient temperature are reported in Figure 8 The figure reflects the approximate temperatures for operations in Oslo, Norway, Atlanta, USA, and Shanghai, China.

[0441] Comparative Example 3 - CO2 Pressurized Supermarket Refrigeration System

[0442] according to Fig.12 The process flow shown provides a CO2 boosting system using a parallel compression system and a mechanical subcooler in a supermarket refrigeration system.

[0443] The system was operated under a range of ambient conditions from about -13°C to about 45°C with R744 and CO2 pressurization under the following conditions.

[0444] Example Name C3(V) illustrate unit refrigerant R744 / CO2 Global Warming Potential (AR5) [-] 1 Refrigerant charge [kg] 1000 Leakage rate [％] 15％ MT evaporation temperature [℃] -6.1 LT evaporation temperature [℃] -28.3 LT / MT cooling load [kW] 87 / 138 Evaporator superheat MT / LT [℃] 5.5 Suction superheat LT [℃] 22.2 Suction superheat MT [℃] 8.3 Isentropic efficiency LT [-] 0.67 Isentropic efficiency MT [-] 0.7 Processing temperature cascade HX [K] — Process temperature condenser [K] 5.5SC, 2.5TC Minimum condensing temperature [℃] 10

[0445] The results of the system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for the COP value) are shown together with the results of Example 5 below. Figure 7 The results of Example C3 (and using the designation V), in terms of equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 8 The results for ambient temperature are reported in Figure 8 The figure reflects the approximate temperatures for operations in Oslo, Norway, Atlanta, USA, and Shanghai, China.

[0446] Comparative Example 4 - R290 Water-Cooled Supermarket Refrigeration System

[0447] The present invention provides an R290 water-cooled supermarket refrigeration system, and the system operates under the following conditions under a series of environmental conditions ranging from about -13°C to about 45°C, using R744 and CO2 pressurization.

[0448] Example Name C4(VI) illustrate unit refrigerant R290 Global Warming Potential (AR5) [-] 3 Refrigerant charge [kg] 750 Leakage rate [％] 10％ MT evaporation temperature [℃] -5.5 LT evaporation temperature [℃] -27.8 LT / MT cooling load [kW] 87 / 138 Evaporator superheat MT / LT [℃] 5.5 Suction superheat LT [℃] 5.5 Suction superheat MT [℃] 5.5 Isentropic efficiency LT [-] 0.52 Isentropic efficiency MT [-] 0.55 Processing temperature cascade HX [K] 5.5 Process Temperature Condenser [K] 5.5 Minimum condensing temperature [℃] 15.5

[0449] The results of the system operation (using R404A in the centralized system of Comparative Example 1 as the COP baseline) are shown together with the results of Example 5 below. Figure 7 The results of Example C4 (and using the name VI), in terms of equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 8 Results are reported for ambient temperature, reflecting approximate temperatures for operations in Oslo, Norway, Atlanta, USA, and Shanghai, China.

[0450] Example 5 - Micro-cascade supermarket refrigeration system

[0451] According to Figure 6 In the process flow shown, the micro-cascade supermarket refrigeration system was operated under a range of ambient conditions ranging from about -13°C to about 45°C with R471A in the high side (MT system) and three different refrigerants (R744, R1234yf and R455A) in the low side (LT system) under the following conditions.

[0452]

[0453] The results of the system operation (using R404A in the centralized system of Comparative Example 1 as the baseline of the COP value) for three sets of environmental conditions, namely 13°C, 30°C and 45°C, together with the results of the above comparative examples are shown in Figure 7 , where the first column in each group represents a 13°C environment, the second column in each group represents a 30°C environment, and the third column in each group represents a 45°C environment. These results show that for each of these ambient temperature conditions, the micro-cascade system of the present invention produces the highest COP among all the tested systems. Similarly, Fig. 9 It is shown that, as a function of ambient temperature, the micro-cascade system of the present invention, designated as Example 5C, produces results significantly better than all tested systems (except the R744 booster system) when the ambient temperature is below about 5° C., and significantly better than all systems, including the R744 booster system, when the temperature is above 5° C. These results are very beneficial and unexpected.

[0454] The results of this example in terms of life cycle performance analysis (equivalent emissions and weighted COP) are shown together with the results of the above-named comparative examples. Figure 8 The emission value is calculated as follows:

[0455] Direct emissions = refrigerant charge (kg) × ((annual leakage × life) + life loss) × GWP

[0456] Indirect emissions = annual energy consumption × lifespan × emission coefficient

[0457] from Figure 8 As can be seen, the example 5C ( Figure 8 The micro-cascade system of the present invention, designated as Example 5C ( Figure 8 The micro-cascade system of the present invention of IV) produces direct and indirect emissions, which direct and indirect emissions even if Fig. 9 The lowest environmental conditions shown in also significantly outperform R404A centralized system, R448A distributed system and R477 / R471A DX cascade system, and it has the lowest emissions of all systems under the environmental conditions represented by Atlanta, USA and Shanghai, China. These results are very beneficial and unexpected. These results also show that the system with the refrigerant with the lowest GWP does not necessarily lead to the lowest emissions. On the contrary, the total emissions of the refrigeration system depend on the energy efficiency of the refrigerant or refrigerant combination in the system and the GWP of one or more refrigerants in the system.

Claims

1. A cascade refrigeration system, comprising: a. A low-level refrigeration circuit, the low-level refrigeration circuit comprising: Low-grade refrigerants with a GWP of about 150 or less; and compressor; b. an inter-circuit heat exchanger in which the low-grade refrigerant condenses; and c. A high-grade refrigeration circuit comprising a high-grade refrigerant, wherein the high-grade refrigerant: (i) has a Class A1 flammability or a Class A2L flammability; (ii) evaporates at a temperature below the condensation temperature of the low-grade refrigerant; and (iii) comprises at least about 77 weight percent HFO-1234ze(E), wherein the high-grade refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the low-grade refrigeration circuit.

2. The cascade refrigeration system according to claim 1, wherein the high-grade refrigerant has a Class A1 flammability.

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

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

5. The cascade refrigeration system according to any one of claims 1 to 4, wherein the low-grade refrigerant comprises 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-grade refrigerant comprises R471A and / or R476A.

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

8. The cascade refrigeration system of claim 1 wherein said low stage refrigeration circuit compressor comprises at least one compressor having a horsepower rating of approximately 2 horsepower or less.

9. A method for providing cooling in an extreme temperature air conditioning system, the method 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, and c. Condensing the refrigerant at a temperature ranging from about 55°C to about 95°C.

10. A method for providing cooling in a high temperature heat pump, the method 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, and c. Condensing the refrigerant at a temperature ranging from about 55°C to about 95°C.

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