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 consists essentially of R454A and a high stage comprises either a class A1 refrigerant or a class A2L refrigerant and comprises at least about 75% by weight of HFO-1234ze (E).

Description

[0001] Cross-references to related applications

[0002] This invention relates to and claims priority to U.S. Application No. 18 / 198,606, filed May 17, 2023, and U.S. Provisional Application No. 63 / 454,325, filed March 24, 2023, each of which is fully incorporated herein as fully set forth below. Technical Field

[0003] This invention relates to highly efficient, low global warming potential (“low GWP”) refrigerants, and to air conditioning and / or refrigeration systems and methods for providing cooling, specifically including cascade refrigeration systems that are safe and effective. Background Technology

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

[0005] One approach has been to use low-GWP refrigerants, such as carbon dioxide (R744) and hydrocarbon refrigerants. However, such approaches used to date can suffer from significant safety and financial disadvantages, such as: poor system energy efficiency leading to increased operating costs; high system complexity leading to high initial system costs; low system maintainability and reliability leading to high maintenance costs; and high system flammability. Systems that include highly flammable refrigerants in existing layouts are particularly disadvantageous because they can lead to poor safety levels; may conflict with regulatory restrictions; and can increase the liability of refrigeration system operators and manufacturers. Safety is of particular concern given 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] Therefore, the applicant has recognized that the refrigeration industry continues to need safe, robust and sustainable methods to reduce the use of high-GWP refrigerants that can be used with existing technologies.

[0007] Figure 1A One such method, which was previously used, is shown. Figure 1A A refrigeration system 100, typically used in commercial refrigeration in supermarkets, is shown. System 100 is a direct expansion system that provides both intermediate and low-temperature refrigeration via an intermediate-temperature refrigeration circuit 110 and a low-temperature refrigeration circuit 120.

[0008] exist Figure 1AIn the typical prior configuration marked 100, the intermediate-temperature refrigeration circuit 110 uses R134a as its refrigerant. The intermediate-temperature refrigeration circuit 110 provides intermediate-temperature cooling and removes waste heat from the low-temperature refrigeration circuit 120 via heat exchanger 130. The intermediate-temperature refrigeration circuit 110 extends between the top panel 140, the machine room 141, and the sales area 142. On the other hand, the low-temperature refrigeration circuit 120 uses R744 as its refrigerant. The low-temperature refrigeration circuit 120 extends between the machine room 141 and the sales area 142. Availablely, as discussed above, R744 has a low GWP.

[0009] However, although Figure 1A The refrigeration systems of the type disclosed herein may provide good efficiency levels, but the applicant has recognized that such systems have at least two major disadvantages: first, such systems use high-GWP refrigerant R134a (R134a has a GWP of about 1300); second, although the low-GWP refrigerant R744 is used in the cryogenic portion of such systems, this refrigerant exhibits many of the aforementioned disadvantages, including significant safety and economic disadvantages.

[0010] Furthermore, in certain refrigeration applications, it is necessary to cool products without exposing them to temperatures below a specific point (such as the freezing point of water). For example, in a supermarket environment, certain products are typically kept at a lower temperature relative to the environment, but simultaneously cooling those products to below the freezing point of water is disadvantageous, especially since preferred cooling methods involve indirect cooling with humid ambient air. For these applications, refrigerant temperatures along the evaporator below the freezing point of water are also disadvantageous, as they will cause frost buildup and thus require defrosting of the equipment. Avoiding frost buildup 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, as it is undesirable to freeze such products at the time of sale. For convenience, the applicant refers to such applications, methods, and systems herein as “non-freezing” applications, methods, and systems.

[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 surface of the swirl tube, thus eliminating the need for defrosting. In such refrigeration applications, systems, and methods, the use of single-component fluids has historically been considered particularly desirable because the saturation temperature of such fluids does not change during evaporation at constant pressure. This is highly desirable because it allows systems or methods to be designed with a refrigerant temperature along the evaporator that remains substantially constant during the evaporation process and above the freezing point of water, assuming little or no pressure drop as the refrigerant flows through the evaporator. Furthermore, product applications often require a small temperature difference between the air and the refrigerant to reduce air dehumidification and subsequently remove moisture content and product mass loss. In such applications, the requirements for a small temperature difference and avoidance of frost formation, as well as the need for a certain degree of positive superheat at the evaporator outlet, can be important when selecting a specific refrigerant. Superheat of zero or less (i.e., refrigerant not overheating) can lead to reduced cooling capacity, reduced efficiency, and potential compressor failure. The term "superheat" or simply "superheat" refers to the temperature of the refrigerant at the evaporator outlet rising above its saturated vapor temperature (or dew point).

[0012] This is Figure 1B The diagram illustrates, by way of example, a typical supermarket product cooling case. Typically, as shown in Figure 1, cooled, humidified air is supplied to the product display area of ​​the case by passing air from outside the case 102 and recirculated air 104 through the heat exchange surface of an evaporator coil 106. This evaporator coil is located within the case, in an area typically separated from (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 this type, it is highly desirable that the cooling space 112 along the evaporator in the refrigeration system always, or substantially always, has a refrigerant temperature above a certain level. For example, in many applications such as product refrigeration, the minimum exhaust (outlet) temperature of the air in the display case is designed to be approximately 2°C to 3°C to provide a safety margin to avoid cooling spaces or products with temperatures below the freezing point of water. Furthermore, to minimize moisture removal from the air and subsequent product drying (mass loss), the temperature difference between the air outlet and the refrigerant needs to be small, typically 2°C to 3°C. This, combined with the fact that the evaporators in these applications require a superheat of approximately 3°C to approximately 5°C, constrains the permissible evaporator slip of the refrigerant, ensuring that the evaporation temperature remains above the freezing point of water, and thus preventing frost buildup.

[0013] Those skilled in the art will know that it has been difficult to provide refrigerants that are multi-component blends of different single-component refrigerants to date, which are the two desired results.

[0014] Prior to this invention, as mentioned above, those skilled in the art had primarily used single-component refrigerants, such as HFC-134a, in such applications with low-temperature sensitivity, and avoided refrigerant blends, as blends generally undergo significant changes in boiling point temperature upon evaporation, which has been considered a major obstacle to determining blends with the correct balance of properties for such systems.

[0015] On the other hand, the applicant has recognized that in many applications, it is also difficult to identify a single-component fluid with a complete set of properties that give it specific advantages in the aforementioned types of applications. For example, in many important applications, it is necessary to identify a refrigerant that simultaneously meets the following conditions: (1) has a feasible slip, i.e., a slip 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 to maintain normal superheat, for example, from about 3°C ​​to about 5°C; (2) is non-flammable (Class A1) or only slightly flammable (Class A2L); (3) has low toxicity or is substantially non-toxic; (4) has a low global warming potential (GWP) (e.g., less than about 150); and (5) has heat transfer and other properties (such as chemical stability) that match the needs of the specific application (especially in intermediate-temperature heat transfer systems, and even more preferably in frost-free or low-frost intermediate-temperature refrigeration systems). While single-component refrigerants can satisfy items (1), (2), and (3) in many cases, those skilled in the art have found it difficult (if not impossible) to date to find most refrigerants, and preferably all (whether single-component or other-component), that satisfy not only items (1), (2), and (3) but also items (4) through (5). Here, non-flammable substances will be classified as "1" by ASHRAE, and low-toxicity substances will be classified as "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-refrigerated applications to date, it cannot meet requirements such as low GWP (item 5 above) because HFC-134a has a GWP of about 1300.

[0017] The applicant proceeded in a manner contrary to conventional wisdom and discovered unexpected and advantageous results. For example, the applicant has found, as detailed below, that specific blends, including carefully selected combinations of components, can possess advantageous but unexpected combinations of non-flammability, while exhibiting excellent heat transfer properties, low GWP (e.g., below about 150), low or non-toxicity, chemical stability, and lubricant compatibility, etc. Furthermore, the applicant has found that the refrigerant compositions of the present invention are particularly advantageous for use in intermediate-temperature refrigeration systems, and especially in cascade and / or intermediate-temperature refrigeration systems where it is desirable to maintain the temperature of cold air above about 0°C and avoid exposing the air to be cooled to temperatures below about 0°C, in order to protect the cooled articles from frost and / or prevent frost formation on the evaporator coils, which in themselves can negatively impact the overall efficiency of such systems due to the need for defrosting and / or inconsistent cooling between the coils. Summary of the Invention

[0018] The applicant has discovered refrigerant compositions, heat transfer compositions containing the refrigerant, 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 cryogenic or non-refrigeration applications described above.

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

[0020] (a) A low-level refrigeration circuit, comprising:

[0021] A low-grade refrigerant comprising at least about 60% by weight of HFO-1234yf and having a GWP of about 150 or less; and

[0022] compressor;

[0023] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0024] (c) An advanced refrigeration circuit comprising an advanced refrigerant that: (i) has A1 or A2L flammability; and (ii) evaporates at a temperature below the condensation temperature of the lower-level refrigerant; and (iii) comprises at least about 77% by weight of HFO-1234ze(E), wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0025] For convenience, the system based on this paragraph is sometimes referred to as System 1A in this document.

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

[0027] (a) A low-level refrigeration circuit, comprising:

[0028] (i) a low-grade refrigerant comprising at least about 60% by weight of HFO-1234yf and having a GWP of about 150 or less and a Class A1 flammability or Class A2L flammability; and

[0029] (ii) Compressor;

[0030] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0031] (c) An advanced refrigeration circuit comprising an advanced refrigerant that: (i) has A1 or A2L flammability; and (ii) evaporates at a temperature below the condensation temperature of the lower-level refrigerant; and (iii) comprises at least about 77% by weight of HFO-1234ze(E), wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0032] For convenience, the system based on this paragraph is sometimes referred to as System 1B in this document.

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

[0034] (a) A low-level refrigeration circuit, comprising:

[0035] (i) a low-grade refrigerant comprising at least about 60 wt% HFO-1234yf and at least about 30 wt% R32 and having a GWP of about 150 or less and a Class A2L or Class A1 flammability; and

[0036] (ii) Compressor;

[0037] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0038] (c) An advanced refrigeration circuit comprising an advanced refrigerant that: (i) has A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the lower-level refrigerant; and (iii) comprises at least about 77% by weight of HFO-1234ze(E), wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0039] For convenience, the system based on this paragraph is sometimes referred to as System 1C in this document.

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

[0041] (a) A low-level refrigeration circuit, comprising:

[0042] (i) a primary refrigerant, which is substantially composed of at least about 60% by weight of HFO-1234yf and at least about 20% by weight of HFC-32; and

[0043] (ii) Compressor;

[0044] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0045] (c) An advanced refrigeration circuit comprising an advanced refrigerant that: (i) has A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the lower-level refrigerant; and (iii) comprises at least about 77% by weight of HFO-1234ze(E), wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0046] For convenience, the system according to this paragraph is sometimes referred to herein as system 2B1. The present invention includes a cascade refrigeration system comprising:

[0047] (a) A low-level refrigeration circuit, comprising:

[0048] (i) a primary refrigerant, which is substantially composed of about 60 wt% to about 70 wt% HFO-1234yf and about 30 wt% to about 40 wt% HFC-32; and

[0049] (ii) Compressor;

[0050] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0051] (c) An advanced refrigeration circuit comprising an advanced refrigerant that: (i) has A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the lower-level refrigerant; and (iii) comprises at least about 77% by weight of HFO-1234ze(E), wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0052] For convenience, the system according to this paragraph is sometimes referred to herein as system 2B2. The present invention includes a cascade refrigeration system comprising:

[0053] (a) A low-level refrigeration circuit, comprising:

[0054] (i) A low-grade refrigerant consisting primarily of R454A;

[0055] (ii) Compressor;

[0056] (iii) Condenser;

[0057] (iv) Evaporator; and

[0058] (v) A suction line heat exchanger, connected between the outlet of the evaporator and the inlet of the compressor, for transferring heat to the evaporator.

[0059] The refrigerant of the compressor;

[0060] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0061] (c) An advanced refrigeration circuit comprising an advanced refrigerant that: (i) has A1 flammability; and (ii) evaporates at a temperature below the condensation temperature of the lower-level refrigerant; and (iii) comprises at least about 77% by weight of HFO-1234ze(E), wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0062] For convenience, the system according to this paragraph is sometimes referred to herein as system 2C1. The present invention includes a cascade refrigeration system comprising:

[0063] (a) A low-level refrigeration circuit, comprising:

[0064] (i) A low-grade refrigerant consisting of R454A;

[0065] (ii) Compressor;

[0066] (iii) Condenser;

[0067] (iv) Evaporator; and

[0068] (v) A suction line heat exchanger, connected between the outlet of the evaporator and the inlet of the compressor, for transferring heat to the evaporator.

[0069] The refrigerant of the compressor;

[0070] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0071] (c) An advanced refrigeration circuit comprising an advanced refrigerant, which is substantially composed of R471 and evaporates at a temperature below the condensation temperature of the lower-level refrigerant, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0072] For convenience, the system according to this paragraph is sometimes referred to herein as system 2C2. The present invention includes a cascade refrigeration system comprising:

[0073] (a) A low-level refrigeration circuit, comprising:

[0074] (i) A low-grade refrigerant consisting primarily of R454A;

[0075] (ii) Compressor;

[0076] (iii) Condenser;

[0077] (iv) Evaporator; and

[0078] (v) A suction line heat exchanger, connected between the outlet of the evaporator and the inlet of the compressor, for transferring heat to the evaporator.

[0079] The refrigerant of the compressor;

[0080] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0081] (c) An advanced refrigeration circuit comprising an advanced refrigerant, which is substantially composed of R471 and evaporates at a temperature below the condensation temperature of the lower-level refrigerant, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0082] For convenience, the system according to this paragraph is sometimes referred to herein as System 2D1. The present invention includes a cascade refrigeration system comprising:

[0083] (a) A low-level refrigeration circuit, comprising:

[0084] (i) A low-grade refrigerant consisting primarily of R454A;

[0085] (ii) Compressor;

[0086] (iii) Condenser;

[0087] (iv) Evaporator; and

[0088] (v) A suction line heat exchanger, connected between the outlet of the evaporator and the inlet of the compressor, for transferring heat to the evaporator.

[0089] The refrigerant of the compressor;

[0090] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0091] (c) An advanced refrigeration circuit comprising an advanced refrigerant consisting essentially of HFO-1234ze(E) and which evaporates at a temperature below the condensation temperature of the lower-level refrigerant, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0092] For convenience, the system according to this paragraph is sometimes referred to herein as system 2D2. The present invention includes a cascade refrigeration system comprising:

[0093] (a) A low-level refrigeration circuit, comprising:

[0094] (i) A low-grade refrigerant consisting primarily of R454A;

[0095] (ii) Compressor;

[0096] (iii) Condenser;

[0097] (iv) Evaporator; and

[0098] (v) A suction line heat exchanger, connected between the outlet of the evaporator and the inlet of the compressor, for transferring heat to the evaporator.

[0099] The refrigerant of the compressor;

[0100] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0101] (c) An advanced refrigeration circuit comprising an advanced refrigerant, which is substantially composed of R-476A and evaporates at a temperature below the condensation temperature of the lower-level refrigerant, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0102] For convenience, the system according to this paragraph is sometimes referred to herein as System 2D3. The present invention includes a cascade refrigeration system comprising:

[0103] (a) A low-level refrigeration circuit, comprising:

[0104] (i) A low-grade refrigerant consisting primarily of R454A;

[0105] (ii) Compressor;

[0106] (iii) Condenser;

[0107] (iv) Evaporator; and

[0108] (v) A suction line heat exchanger, connected between the outlet of the evaporator and the inlet of the compressor, for transferring heat to the evaporator.

[0109] The refrigerant of the compressor;

[0110] (b) An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and

[0111] (c) An advanced refrigeration circuit comprising an advanced refrigerant, which is substantially composed of R-482A and evaporates at a temperature below the condensation temperature of the lower-level refrigerant, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

[0112] For convenience, the system according to this paragraph is sometimes referred to herein as System 2D4. The invention also includes a cascade refrigeration system comprising:

[0113] (a) A low-level refrigeration circuit, comprising:

[0114] (i) a low-grade A2L refrigerant comprising 63 to 67 wt% HFO-1234yf and 33 to 37 wt% HFC-32; and

[0115] (ii) Compressor;

[0116] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0117] (c) An advanced refrigeration circuit comprising an A1 refrigerant, which is essentially composed of R471A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0118] For convenience, the system according to this paragraph is sometimes referred to herein as system 3A1. The invention also includes a cascade refrigeration system comprising:

[0119] (a) A low-level refrigeration circuit, comprising:

[0120] (i) a low-grade A2L refrigerant comprising 63 to 67 wt% HFO-1234yf and 33 to 37 wt% HFC-32; and

[0121] (ii) Compressor;

[0122] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0123] (c) An advanced refrigeration circuit comprising an A1 refrigerant, which is substantially composed of R1234ze(E), wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0124] For convenience, the system according to this paragraph is sometimes referred to herein as system 3A2. The invention also includes a cascade refrigeration system comprising:

[0125] (a) A low-level refrigeration circuit, comprising:

[0126] (i) a low-grade A2L refrigerant comprising 63 to 67 wt% HFO-1234yf and 33 to 37 wt% HFC-32; and

[0127] (ii) Compressor;

[0128] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0129] (c) An advanced refrigeration circuit comprising an A1 refrigerant, which is essentially composed of R476A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0130] For convenience, the system according to this paragraph is sometimes referred to herein as system 3A3. The invention also includes a cascade refrigeration system comprising:

[0131] (a) A low-level refrigeration circuit, comprising:

[0132] (i) a low-grade A2L refrigerant comprising 63 to 67 wt% HFO-1234yf and 33 to 37 wt% HFC-32; and

[0133] (ii) Compressor;

[0134] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0135] (c) An advanced refrigeration circuit comprising an A1 refrigerant, which is essentially composed of R482A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0136] For convenience, the system according to this paragraph is sometimes referred to herein as system 3A4. The invention also includes a cascade refrigeration system comprising:

[0137] (a) Multiple low-level refrigeration circuits, each low-level refrigeration circuit comprising:

[0138] (i) a low-grade A2L refrigerant comprising 64 wt% to 66 wt% HFO-1234yf and 34 wt% to 36 wt% HFC-32; and

[0139] (ii) Compressor;

[0140] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0141] (c) An advanced refrigeration circuit consisting essentially of R471A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about 15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0142] For convenience, the system according to this paragraph is sometimes referred to herein as system 4A1. The invention also includes a cascade refrigeration system comprising:

[0143] (a) Multiple low-level refrigeration circuits, each low-level refrigeration circuit comprising:

[0144] (i) a low-grade A2L refrigerant comprising 64 wt% to 66 wt% HFO-1234yf and 34 wt% to 36 wt% HFC-32; and

[0145] (ii) Compressor;

[0146] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0147] (c) An advanced refrigeration circuit consisting essentially of R1234ze, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about 15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0148] For convenience, the system according to this paragraph is sometimes referred to herein as system 4A2. The invention also includes a cascade refrigeration system comprising:

[0149] (d) Multiple low-level refrigeration circuits, each low-level refrigeration circuit including:

[0150] (i) a low-grade A2L refrigerant comprising 64 wt% to 66 wt% HFO-1234yf and 34 wt% to 36 wt% HFC-32; and

[0151] (ii) Compressor;

[0152] (e) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0153] (f) An advanced refrigeration circuit consisting essentially of R476A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about 15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0154] For convenience, the system according to this paragraph is sometimes referred to herein as system 4A3. The invention also includes a cascade refrigeration system comprising:

[0155] (g) Multiple low-level refrigeration circuits, each low-level refrigeration circuit including:

[0156] (i) a low-grade A2L refrigerant comprising 64 wt% to 66 wt% HFO-1234yf and 34 wt% to 36 wt% HFC-32; and

[0157] (ii) Compressor;

[0158] (h) An inter-loop heat exchanger, wherein the lower-grade refrigerant condenses preferably in a temperature range of about -5°C to about -15°C; and

[0159] (i) An advanced refrigeration circuit consisting essentially of R482A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about 15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0160] For convenience, the system according to this paragraph is sometimes referred to herein as system 4A1. The invention also includes a cascade refrigeration system comprising:

[0161] (a) Multiple low-level refrigeration circuits, each low-level refrigeration circuit comprising:

[0162] (i) a low-grade refrigerant consisting primarily of R454A; and

[0163] (ii) Compressor;

[0164] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0165] (c) An advanced refrigeration circuit, which includes refrigerant A1, which is essentially...

[0166] The above is composed of R471A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably evaporates in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-loop heat exchanger by absorbing heat from the lower refrigerant.

[0167] For convenience, the system according to this paragraph is sometimes referred to herein as system 4B1. The invention also includes a cascade refrigeration system comprising:

[0168] (a) Multiple low-level refrigeration circuits, each low-level refrigeration circuit comprising:

[0169] (i) a low-grade refrigerant consisting primarily of R454A; and

[0170] (ii) Compressor;

[0171] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0172] (c) An advanced refrigeration circuit comprising an A1 refrigerant, which is essentially composed of HFO-1234ze(E), wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0173] For convenience, the system according to this paragraph is sometimes referred to herein as system 4B2. The invention also includes a cascade refrigeration system comprising:

[0174] (a) Multiple low-level refrigeration circuits, each low-level refrigeration circuit comprising:

[0175] (i) a low-grade refrigerant consisting primarily of R454A; and

[0176] (ii) Compressor;

[0177] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0178] (c) An advanced refrigeration circuit comprising a refrigerant substantially composed of R476A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0179] For convenience, the system according to this paragraph is sometimes referred to herein as system 4B3. The invention also includes a cascade refrigeration system comprising:

[0180] (a) Multiple low-level refrigeration circuits, each low-level refrigeration circuit comprising:

[0181] (i) a low-grade refrigerant consisting primarily of R454A; and

[0182] (ii) Compressor;

[0183] (b) An inter-loop heat exchanger, wherein the lower-grade refrigerant preferably condenses in the inter-loop heat exchanger within a temperature range of about -5°C to about -15°C; and

[0184] (c) An advanced refrigeration circuit comprising a refrigerant substantially composed of R482A, wherein the advanced refrigerant evaporates at a temperature below the condensation temperature of the lower refrigerant, and preferably in the range of about -5°C to about -15°C, wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the lower refrigerant.

[0185] For convenience, the system described in this paragraph is sometimes referred to as System 4B4 in this document.

[0186] This invention includes a cascade refrigeration system (including each of systems 1 to 4), wherein the lower-level refrigeration circuit comprises a plurality of lower-level refrigeration circuits. For convenience, the system according to this paragraph is sometimes referred to herein as system 5A.

[0187] This invention includes a cascade refrigeration system (comprising each of systems 1 to 4), wherein the lower-level 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.

[0188] This invention includes a cascaded refrigeration system (including each of systems 1 to 4), wherein the low-level refrigeration circuit comprises a plurality of independently assembled low-level refrigeration circuits, wherein at least two of such low-level circuits are contained in separate modular refrigeration units, and each of the modular refrigeration units is located in a first area open to the public. For convenience, the system according to this paragraph is sometimes referred to herein as system 5C.

[0189] This invention includes a cascade refrigeration system (comprising each of systems 1 to 5), wherein the compressor in each of the lower 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.

[0190] This invention includes a cascade refrigeration system (comprising each of systems 1 to 6), wherein the lower refrigerant condenses in the inter-loop heat exchanger over a temperature 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.

[0191] The present invention also provides a medium-temperature refrigeration system and method, as detailed below.

[0192] In addition, the applicant has recognized 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 about 1°C to 2°C.

[0193] The methods and systems of the present invention include those that enable the use and implementation of efficient heat exchanger designs, particularly for applications such as reversible heat pumps, wherein the refrigerant flow changes direction in the heat exchanger depending on the operating mode (cooling or heating). Attached Figure Description

[0194] Figure 1A A typical cascade refrigeration system is illustrated schematically.

[0195] Figure 1B A typical supermarket product cooling cabinet is shown schematically.

[0196] Figure 2 A cascade refrigeration system applicable according to the present invention is shown.

[0197] Figure 3 An alternative cascade refrigeration system applicable according to the present invention is shown.

[0198] Figure 4 A cascade refrigeration system using a flooded evaporator is shown.

[0199] Figure 5A and Figure 5B Refrigeration systems with and without suction line heat exchangers are shown respectively.

[0200] Figure 6 The heat transfer system of Example 5 is shown.

[0201] Figure 7 The heat transfer system described in Comparative Example 1 is shown.

[0202] Figure 8 The COP results for Example 5 and Comparative Examples 1 to 4 are shown in graphical form.

[0203] Figure 9 The heat transfer system described in Comparative Example 2 is shown.

[0204] Figure 10 The heat transfer system described in Comparative Example 3 is shown.

[0205] Figure 11 The emissions and weighted COP results for Example 5 and Comparative Examples 1 to 4 are shown in graphical form.

[0206] Figure 12 The system COP of Example 5 and Comparative Examples 1 to 4 is shown in graph form as a function of ambient temperature.

[0207] Description of preferred compositions

[0208] definition :

[0209] As used herein, the terms “low-level” and “high-level” are used in a relative context to refer to the relative evaporation temperatures of two or more cascaded refrigeration loops. Therefore, in the context of a cascaded refrigeration system, the term “low-level” refers to a refrigeration loop in which the refrigerant evaporates at a temperature lower than the evaporation temperature of the refrigerant in the “high-level” loop.

[0210] As used herein, the term "cascade refrigeration" refers to a refrigeration system having a lower-level refrigerant vapor that is cooled at least in part by dissipating heat to a higher-level refrigerant and is preferably condensed.

[0211] The phrase “coefficient of performance” (hereinafter referred to as “COP”) is a generally accepted measure of refrigerant performance, particularly used to indicate the relative thermodynamic efficiency of a refrigerant in a specific heating or cooling cycle involving refrigerant evaporation or condensation. In refrigeration engineering, the term represents the ratio of available cooling or refrigeration capacity to the energy exerted by the compressor when compressing the vapor, and thus the ability of a given compressor to pump heat for a given volumetric flow rate of a heat transfer fluid such as a refrigerant. In other words, given a particular compressor, a refrigerant with a higher COP will deliver more cooling or heating power. One method for estimating the COP of a refrigerant under specific operating conditions is to estimate it from the thermodynamic properties of the refrigerant using standard refrigeration cycle analysis techniques (see, for example, RCDowning, Fluorocarbon Refrigerants Handbook, Chapter 3, Prentice-Hall, 1988, the full text of which is incorporated herein by reference).

[0212] The phrase “Global Warming Potential” (hereinafter “GWP”) has evolved to allow comparisons of the global warming effects of different gases. It compares the heat captured by a given mass of a gas over a specific time period with the heat captured by a similar mass of carbon dioxide. Carbon dioxide was chosen as the reference gas by the Intergovernmental Panel on Climate Change (IPCC), and its GWP is set to 1. The higher the GWP, the warmer the Earth is compared to CO2 over that time period given the gas. As used herein, the term GWP refers to the GWP value measured according to the 2014 IPCC Fifth Assessment Report (hereinafter referred to as AR5).

[0213] The term "non-flammable" refers to a compound or composition that is determined to be non-flammable under the conditions described in ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification and Annex B1 of ASHRAE Standard 34-2016 according to the ASTM Standard E-681-2009 standard test method for flammability concentration limits of chemicals (vapors and gases) (as various standards existed prior to the filing date of this application) (the full text of which is incorporated herein by reference ("non-flammability test")). 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. Non-flammable substances are classified as Class "1" according to ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification (as various standards existed prior to the filing date of this application).

[0214] As used herein, the term "evaporator slip" 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.

[0215] As used herein, the phrase "non-toxic or low toxicity" means that the composition is classified as "Class A" according to ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification and is described in Annex B1 of ASHRAE Standard 34-2016 (if any standards existed prior to the filing date of this application). Non-flammable and low toxicity substances are classified as "Class A1" according to ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification and are described in Annex B1 of ASHRAE Standard 34-2016 (if any standards existed prior to the filing date of this application).

[0216] The term "superheat" or simply "superheat" refers to the temperature of the refrigerant at the evaporator outlet rising above the refrigerant's saturated vapor temperature (or dew point temperature).

[0217] As used herein, the terms R1234yf and HFO-1234yf refer to 2,3,3,3-tetrafluoropropylene.

[0218] As used herein, the terms R1234ze(E), HFO-1234ze(E), and E-1,3,3,3-tetrafluoropropylene refer to the trans isomer of HFO-1234ze.

[0219] As used herein, the term “E-1,1,1,4,4,4-hexafluoro-2-butene” refers to the trans isomer of HFO-1336mzz and is abbreviated as HFO-1336mzz(E).

[0220] As used in this article, the term “1,1,1,2,3,3,3-heptafluoropropane” is abbreviated as HFC-227ea.

[0221] As used herein, the term “cryogenic refrigeration” refers to a refrigeration system that operates under or within the following conditions: (a) a condenser temperature of about 15°C to about 50°C; and (b) an evaporator temperature of about -40°C to about or less than about -15°C.

[0222] As used herein, the term “intermediate temperature refrigeration” refers to a refrigeration system that utilizes one or more compressors and operates under or within the following conditions: (a) a condenser temperature of about 15°C to about 60°C; and (b) an evaporator temperature of about -15°C to about 5°C.

[0223] 1Myhre,G.,D.Shindell,F.-M.Bréon,W.Collins,J.Fuglestvedt,J.Huang,D.Koch,J.-F.Lamarque,D.Lee,B.Mendoza,T.Nakajima,A.Roback,G.

[0224] Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis.

[0225] Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, TF, D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex, and PM Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom

[0226] And New York, NY, USA.

[0227] https: / / www.ipcc.ch / pdf / assessmentreport / ar5 / wg1 / WG1AR5_Chapter08_FINAL.pdf (Pages 73-79)

[0228] As used herein, the term "extreme temperature air conditioning system" refers to a vapor compression air conditioning system in which the refrigerant condenses at a temperature of approximately 55°C to approximately 95°C.

[0229] As used herein, the term "high-temperature heat pump system" refers to a vapor compression system that can operate in a heating mode, wherein the refrigerant condenses at a temperature of approximately 55°C to approximately 95°C.

[0230] As used herein, the term "R454A" refers to the refrigerant designated 454C by ASHRAE, and it consists of 35% (preferably +1 / -1%) of R-32 and 65% (preferably +1 / -1%) of HFC-1234yf.

[0231] As used herein, the term “R454C” refers to the refrigerant designated 454C by ASHRAE, which consists of 21.5% +2 / -2% R-32 and 78.5% -2 / -2% HFC-1234yf.

[0232] As used herein, the term "R455A" refers to the refrigerant designated 455AC by ASHRAE, which consists of 21.5% +2 / -1% R-32, 75.5% HFC-1234yf +2 / -2% and 3% +2 / -1% CO2.

[0233] As used herein, the term "R471A" refers to the refrigerant designated 471A by ASHRAE, which consists 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.

[0234] As used herein, the term "R476A" refers to the refrigerant designated 476A by ASHRAE, which consists of 78.7% + / - 0.5% + / - 2% HFC-1234ze(E), 12% + / - 2% + / - 0.5% HFC-1336mzz(E), and 10% + / - 2% + / - 0.51% HFC-134a.

[0235] As used herein, the term “R482A” refers to the refrigerant designated 482A by ASHRAE, which consists of 10% 134a, 83.5% HFC-1234ze(E), and 6.5% 1224yd.

[0236] As used herein, the term “about” in relation to quantities expressed as a weight percentage means that the amount of the component can vary by + / - 2 wt%.

[0237] Cascade system

[0238] This invention includes a cascade refrigeration system (comprising each of systems 1 to 7), wherein the inter-loop heat exchanger is a flooded heat exchanger, and wherein the advanced refrigerant evaporates in the heat exchanger by absorbing heat from the cryogenic refrigerant. As used herein, references to numbering systems or groups of numbering systems as defined herein refer to each numbering system in such a system, including each system having an in-group number, including any numbering system with a suffix. For example, a reference to system 1 includes a reference to each of systems 1A, 1B, and 1C.

[0239] 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 not exceeding 1°C above the boiling point of the liquid refrigerant in the heat exchanger.

[0240] The present invention also includes a cascade refrigeration system (including each of systems 1 to 7), wherein the low-level refrigeration circuit includes one or more cryogenic refrigeration circuits, and preferably multiple cryogenic refrigeration circuits.

[0241] The present invention also includes a cascade refrigeration system (including each of systems 1 to 7), wherein the lower-level refrigeration circuit includes one or more cryogenic refrigeration circuits, preferably multiple cryogenic refrigeration circuits, and wherein the higher-level refrigeration circuit includes one or more medium-temperature refrigerant circuits.

[0242] In a preferred embodiment (in each of systems 1 to 7), the advanced refrigeration circuit is located substantially entirely outside the lower-level refrigeration unit. As used herein, the term "substantially entirely outside" means that the advanced components are typically located away from the lower-level refrigeration unit, except that conduits, etc., which can be considered part of the advanced circuit, may enter into or be located near or between the lower-level circuit to provide heat exchange between the lower-level and advanced refrigerants via an inter-circuit heat exchanger.

[0243] In a preferred embodiment (in each of systems 1 to 7), the low-level loop includes one or more “cooling units,” and preferably “cryogenic cooling units.” As used herein, the term “cooling unit” refers to a structure that is at least partially enclosed and / or fully enclosed, capable of providing cooling within at least a portion of the structure, and structurally different from any structure that is enclosed or contains a high-level loop.

[0244] In a preferred embodiment (in each of systems 1 to 7), the advanced loop includes one or more “cooling units”, and preferably “medium-temperature cooling units”.

[0245] The advanced loop in the cascade system of the present invention (in each of systems 1 to 7) may also include a fluid receiver for receiving advanced refrigerant from the condenser in the advanced loop.

[0246] Each refrigeration unit (included in each of systems 1 to 7) may be located within a first area. The first area may be a store area. This means that each first refrigeration circuit (preferably a low-temperature refrigeration circuit) may also be located within the first area, such as within the store floor.

[0247] 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 located within the refrigeration unit. Each evaporator in the lower stage of such preferred refrigeration units may be positioned to refrigerate its respective space / object, preferably by cooling the air within the space to be refrigerated.

[0248] As described above, the advanced refrigeration circuit of the present invention (included in each of systems 1 to 7, and preferably when the advanced circuit includes a medium-temperature refrigeration circuit) may have components extending between a first low-level circuit (preferably a low-temperature refrigeration unit) and at least a second region remote from said low-level circuit. The second region may be, for example, a machine room that houses most of the components of the advanced circuit.

[0249] The advanced refrigeration circuit of the present invention (including each of systems 1 to 7, preferably including a medium-temperature refrigeration circuit) can extend to a second and a third region. The third region can be an area outside one or more buildings where the lower-level circuit is located. This allows ambient cooling to be utilized.

[0250] Unless otherwise specified herein for a particular implementation, the refrigerant in an advanced refrigeration circuit may be non-flammable, i.e., classified as A1 under ASHRAE 34 (as measured by ASTM E681) or A2L under ASHRAE 34 (as measured by ASTM E681). This may be desirable in cases where advanced circuits involve long pipes extending between different areas of a building: for example, between a shop floor (where lower-level refrigeration units may be deployed) and a machine room. Therefore, having flammable refrigerants in advanced refrigeration circuits may be unsafe because both the risk and the severity of potential leaks increase as the advanced circuit spans a larger area, thereby exposing more people and / or structures to fire risk.

[0251] Each primary refrigeration circuit (included in each of systems 1 to 7) may include at least one fluid expansion device. The at least one fluid expansion device may be a capillary tube or a fixed orifice. This means that simpler flow control devices, such as capillary tubes and orifice tubes, can and are preferably advantageous for use in the primary refrigeration circuits of the present invention (included in each of systems 1 to 7).

[0252] One embodiment of the cascade refrigeration system according to the present invention is as follows: Figure 2 It is illustrated schematically and described in detail below.

[0253] Figure 2 A cascade refrigeration system 200 is shown. More specifically, Figure 2 A refrigeration system 200 with three low-level refrigeration circuits 220a, 220b, and 220c is shown. Each of the low-level refrigeration circuits 220a, 220b, and 220c has 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 shown by a single icon, it should be understood that the compressor, evaporator, heat exchanger, expansion valve, etc., may each comprise multiple such units. In each circuit 220a, 220b, and 220c, the evaporator 223, compressor 221, heat exchanger 230, and expansion valve 222 are connected in series with each other in the listed order. Each of the low-level refrigeration circuits 220a, 220b, and 220c is contained within a separate corresponding refrigeration unit (not shown). In this example, each of the three refrigeration units is preferably a refrigeration unit, and the refrigeration unit houses the corresponding cryogenic refrigeration circuit. Thus, each refrigeration unit includes a self-contained and dedicated cryogenic refrigeration circuit. The refrigeration unit (not shown) and therefore the low-temperature refrigeration circuits 220a, 220b, 220c can be arranged, for example, in the sales area 242 of a supermarket.

[0254] In this example, the refrigerant in each of the lower-level refrigeration circuits 220a, 220b, and 220c is a low-GWP refrigerant, such as CO2, propane, HFO-1234yf, R454A, R454C, R455A, or a combination of two or more of these. As those skilled in the art will understand, the refrigerant in each of the lower-level circuits 220a, 220b, and 220c may be the same as or different from the refrigerant in each of the other lower-level refrigeration circuits 220a, 220b, and 220c, but in a preferred embodiment, each of the plurality of lower-level circuits comprises CO2, propane, HFO-1234yf, R454A, R454C, R455A, or a combination of two or more of these.

[0255] The refrigeration system 200 also includes an advanced refrigeration circuit 210. The advanced refrigeration circuit 210 includes a compressor 211, a condenser 213, and a fluid receiver 214. The compressor 211, condenser 213, and fluid receiver 214 are connected in series in a given order. Although each of the compressor, condenser, fluid receiver, etc., in the advanced circuit is shown by a single icon, it should be understood that the compressor, evaporator, heat exchanger, expansion valve, etc., may each include multiple such units. The advanced refrigeration circuit 210 also has four parallel-connected branches: three intermediate-temperature cooling branches 217a, 217b, and 217c, which are not in heat transfer communication with the lower-level refrigeration circuit; and a lower-level 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 intermediate-temperature cooling branches 217a, 217b, and 217c has expansion valves 218a, 218b, and 218c, and evaporators 219a, 219b, and 219c, respectively. Expansion valves 218a and evaporators 219 are connected in series and in a given order between fluid receiver 214 and condenser 211. In a preferred embodiment, the advanced circuit 220, including the cryogenic cooling branch 216, has an expansion valve 212 and interfaces in the form of inlet and outlet pipes, conduits, valves, etc. (collectively referred to as 260a, 260b, and 260c, respectively), which carry advanced refrigerant liquid to each of the inter-loop heat exchangers 230a, 230b, and 230c and remove advanced refrigerant vapor from each inter-loop heat exchanger, as shown in the preferred embodiment, which are located within the refrigeration unit 220. The cryogenic cooling branch 216 connects with each of the inter-loop heat exchangers 230a, 230b, and 230c at corresponding loop junction positions 231a, 231b, and 231c. Each loop junction position 231a, 231b, and 231c is arranged in a series-parallel combination with each of the other loop junction positions 231a, 231b, and 231c.

[0256] The advanced refrigeration circuit 210 has components extending between the sales area 242, the machine room 241, and the ceiling 140. Cooling branches 216 and the intermediate-temperature branches 218a, 218b, and 218c of the intermediate-temperature refrigeration circuit 210 are preferably located in the sales area 242. The compressor 211 and fluid receiver 214 are preferably located in the machine room 241. The condenser 213 is preferably located in a location easily exposed to environmental conditions, such as on the ceiling 240.

[0257] In this example, the refrigerant in the advanced refrigeration circuit 210 comprises, is substantially composed of, or is composed of: a refrigerant comprising at least about 75% by weight of HFO-1234ze and having A1 or A2L flammability. The invention includes a cascade system in which the refrigerant in the advanced refrigeration circuit 210 comprises, is substantially composed of, or is composed of HFO-1234ze(E), R471A and / or R476A and / or 482A. Further advantageously, the blend has a low GWP, making it an environmentally friendly solution, and exhibits excellent heat transfer properties, as described below in its embodiments.

[0258] like Figure 2 As shown, the uses of the preferred implementation scheme can be summarized as follows:

[0259] • Each of the low-level refrigeration circuits 220a, 220b, and 220c absorbs heat via its evaporator 223 to provide low-temperature cooling to the space to be cooled (not shown);

[0260] • Advanced refrigeration circuit 210, via branch circuit 216, connects to inter-circuit heat exchangers 230a, 230b,

[0261] Each of the components in 230c absorbs heat to cool and condense from the lower circuit 220a.

[0262] Low-grade refrigerant vapor in the corresponding compressor of each of 220b and 220c;

[0263] • The advanced refrigeration circuit 210 absorbs heat at each of the evaporators 219 to provide medium-temperature cooling to the space to be cooled (not shown); and

[0264] • Heat is removed from the refrigerant in the advanced refrigeration circuit 210 in the air-cooled cooler 213.

[0265] Usable Figure 2 The present invention arrangement of the type shown achieves several advantageous results, particularly the self-contained refrigeration circuit 230 in each of the corresponding refrigeration units.

[0266] For example, the installation and removal of the refrigeration units and the overall cascade refrigeration system 200 are simplified. This is because the refrigeration units, with their built-in self-contained refrigeration circuits 220a, 220b, and 220c, can be easily connected to or disconnected from the advanced refrigeration circuit 210 without altering the refrigeration circuits 220a, 220b, and 220c. In other words, the refrigeration units can be simply "inserted" into or removed from the advanced refrigeration circuit 210.

[0267] Another advantage is that each refrigeration unit (including its corresponding first refrigeration circuits 220a, 220b, 220c) can be factory tested at default values ​​before being installed into the real-time refrigeration system 200. This reduces the likelihood of malfunctions, including potentially harmful refrigerant leaks. Therefore, a reduced leakage rate can be achieved.

[0268] In a preferred embodiment, another advantage is that a flooded inter-loop heat exchanger is provided in the system of the present invention (including each of systems 1 to 7), thereby improving heat transfer between lower and higher stages. Therefore, the overall efficiency of the refrigeration system is improved.

[0269] In a preferred embodiment (including each of systems 1 to 7), the present invention further includes a cascade refrigeration system comprising: a plurality of cryogenic refrigeration loops, wherein each cryogenic refrigeration loop includes a cryogenic refrigerant having a GWP of about 150 or less and including at least about 50 wt% or at least about 60 wt% of R1234yf (specifically including one or more of R-454A or R454A and additional R-454C and / or R455A), and a compressor having an output power of about 3.5 kW or less; and an inter-loop heat exchanger, wherein the cryogenic refrigerant exchanges heat between the loops. The device condenses in a temperature range of about -5°C to about -15°C; and includes a medium-temperature refrigeration circuit containing a medium-temperature refrigerant, wherein the medium-temperature refrigerant comprises, is substantially composed of, or is composed of at least about 75% by weight of HFO-1234ze(E) (specifically including R471A and / or R476A and / or R482A), and an evaporator, wherein the medium-temperature refrigerant evaporates at a temperature below the condensation temperature of the low-temperature refrigerant and evaporates in a temperature 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.

[0270] In a preferred embodiment (including each of systems 1 to 7), the invention further includes a cascade refrigeration system comprising: a plurality of cryogenic refrigeration loops, wherein each cryogenic refrigeration loop includes a cryogenic refrigerant having a GWP of about 150 or less and including at least about 50 wt% or at least about 60 wt% of R1234yf (specifically including R454A and combinations of R454A with R-454C and / or R-455A); and a compressor having a compression power of two horsepower or less; an inter-loop heat exchanger, wherein the cryogenic refrigerant is heated in the inter-loop heat exchanger at approximately - Condensation in a temperature range of about 5°C to about -15°C; and a medium-temperature refrigeration circuit comprising a medium-temperature refrigerant, wherein the medium-temperature refrigerant comprises, is substantially composed of, or is composed of at least about 75% by weight of HFO-1234ze(E) (specifically including R471A and / or R476A and / or R482A), and an evaporator wherein the medium-temperature refrigerant evaporates at a temperature below the condensation temperature of the low-temperature refrigerant and evaporates in a temperature 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.

[0271] Cascade Refrigeration System - Alternative Solution

[0272] Those skilled in the art will recognize from the teachings contained herein that any number of low-level cooling circuits 220 may exist in accordance with the present invention (including each of systems 1 to 7). Specifically, the number of low-level circuits 220 may be as many as the cooling unit to be cooled. Therefore, the high-level cooling circuit 210 may interface with any number of low-level cooling circuits 220, and vice versa.

[0273] Those skilled in the art will readily understand from the teachings contained herein that any number and arrangement of high-level loop branches 217 and evaporators 218 can exist according to the invention (including each of systems 1 to 4). In an alternative arrangement according to the invention (including each of systems 1 to 7), each low-level loop 220 may be arranged in complete parallel with each other low-level loop 220. Examples of such arrangements are shown in Figure 3 middle. Figure 3 System 300 is shown, in which each loop interface location of the inter-loop heat exchangers 231a, 231b, 231c is arranged in complete parallel with each of the other loop interface locations. The components of system 300 are otherwise similar to those of system 200 (see reference). Figure 2 The components of system 300 operate in substantially the same manner as those of system 200, but it should be understood that the performance of the overall system and other important features of the overall system can be significantly affected by this arrangement change.

[0274] Usefully, this means that a given portion of the refrigerant from the advanced loop 210 passes through only one inter-loop heat exchanger 230 before returning to the compressor 211. This arrangement thus ensures that each of the heat exchangers 230 will receive advanced refrigerant at approximately the same temperature, as this arrangement prevents any heat exchanger from receiving a portion of the refrigerant that has been preheated by passing through an upstream heat exchanger, as is the case in a series arrangement.

[0275] It will be apparent to those skilled in the art, based on the teachings contained herein, that various other arrangements of the loop interface locations 231a, 231b, 231c relative to one and the advanced cooling loop 210 can be implemented and practically conceived according to the present invention (including each of systems 1 to 7).

[0276] Those skilled in the art will readily recognize from the teachings contained herein that the preferred modular design of the lower-level loops (including each of systems 1 to 7) of the preferred embodiments of the invention allows the use of non-flammable, low-pressure refrigerants with relatively low GWP.

[0277] Cascade refrigeration system with flooded evaporator

[0278] Now refer to Figure 4 The preferred refrigeration system of the present invention is illustrated and described by way of example. The figure schematically shows a cascade refrigeration system 400 having an advanced refrigeration circuit 410 with a receiver 414 for 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, having two primary refrigeration circuits 420a and 420b. Each primary refrigeration circuit 420a and 420b has an evaporator 423, a compressor 421, an inter-circuit heat exchanger 431, and an expansion valve 422. In each circuit 420a and 420b, the evaporator 423, compressor 421, heat exchanger 431, and expansion valve 422 are connected in series with each other in the listed order. Each primary refrigeration circuit 420a and 420b is preferably housed in a corresponding refrigeration unit (not shown). In a preferred example, each primary refrigeration circuit is included in a refrigeration unit, and the refrigeration unit houses its corresponding primary refrigeration circuit. Thus, each refrigeration unit is provided with an independent and dedicated refrigeration circuit. In a preferred embodiment, the refrigeration unit (not shown) and therefore the primary refrigeration circuits 420a and 420b are positioned in the supermarket sales area 462.

[0279] Receiver 414 is arranged to separate the gaseous and liquid refrigerant after it passes through expansion valve 418, such that the refrigerant allowed to pass through the intermediate-temperature cooling branch 417 and the cryogenic cooling branch 416, and thus through the evaporator 419 and heat exchangers 430a, 430b, is essentially 100% liquid. Another key feature of the refrigeration system 400 is pump 442. Pump 442 drives the refrigerant to the intermediate-temperature branch 417 and the cryogenic branch 416. In an alternative system arrangement, the density difference between the liquid and gaseous phases of the refrigerant drives the system, and no pump or fan is required.

[0280] In this example, the low-grade refrigerant in refrigeration circuits 420a and 420b comprises, is substantially composed of, or consists of a low-GWP non-flammable (Class A1) refrigerant comprising at least about 50% by weight, or at least about 60% by weight, of R1234yf (specifically including R-454A or a combination of R454A with R-454C and / or R455A). Those skilled in the art will recognize that the refrigerant in each of the refrigeration circuits 420a and 420b may be the same as or different from the refrigerant in the other of the first refrigeration circuits 420a and 420b.

[0281] The refrigeration system 400 also includes 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, condenser 413, and 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.

[0282] 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 and 441 are controllable, allowing control over the amount of refrigerant flowing in each of the compressor branch 450 and the ambient cooling branch 451. The first control valve 440 is connected in series with a pump 442.

[0283] The advanced refrigeration circuit 410 also has two additional branches connected in parallel: a medium-temperature cooling branch 417 and a low-temperature cooling branch 416, which supply liquid refrigerant to the inter-loop heat exchanger 431. The medium-temperature cooling branches 417 and 416 are connected between the pump 442 and the second controllable valve 441. The medium-temperature cooling branch 417 has an evaporator 419. The low-temperature cooling branch 416 intersects with each of the inter-loop heat exchangers 430a and 430b of the first refrigeration circuits 420a and 420b at corresponding loop interface positions 431a and 431b. Each of the loop interface positions 431a and 431b forms a series-parallel combination with the other loop interface positions 431a and 431b.

[0284] The cascade system 400 includes components that extend the high-level and low-level circuits between the sales area 462, the machine room 461, and the ceiling 440. Branches 416 and 417, which carry the high-level liquid refrigerant to the inter-circuit heat exchanger, are preferably each primarily located in the sales area 462. "Primarily located in the sales area 462" means that circuit locations 431a, 431b, and the evaporator 419 are located in or very close to the sales area 462. However, the junctions 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, may be located in the machine room 461.

[0285] In a preferred embodiment, compressor branch 450 includes components that extend the branch between machine room 461 and ceiling 460. More specifically, compressor 411, expansion valve 418, and flood receiver 414 are preferably located in machine room 461. Condenser 413 is preferably located in a location where ambient air can be easily accessed, such as on ceiling 460.

[0286] 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 in a place where it can easily access ambient air, such as on the ceiling 603.

[0287] 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.

[0288] In this example, the refrigerant in the advanced circuit 410 preferably comprises, is substantially composed of, or is composed of at least about 75% by weight of HFO-1234ze(E) (specifically including R471A and / or R476A and / or 482A).

[0289] Despite the structural differences, refrigeration system 400 operates in a manner similar to refrigeration system 200 in use, but with the following key differences. First, the receiver in the advanced refrigeration loop 410 of refrigeration system 400 causes the inter-loop heat exchangers 430a and 430b to be flooded evaporators for the advanced loop, and the intermediate temperature evaporator 419 is also a flooded evaporator.

[0290] Those skilled in the art will recognize, based on the disclosure and teachings contained herein, that using the refrigeration arrangement according to the invention (including each of the cascade systems 1 to 7) has several advantages, which uses a flooded evaporator, as disclosed, for example, in system 400.

[0291] The applicant has discovered that one such advantage is an unexpected increase in the coefficient of performance (COP). Not bound by any particular theory, this unexpected advantage is believed to be partly due to the need for less compressor 411 to operate and the increased cooling capacity of the second refrigeration circuit 410, as the system allows for superheating of the refrigerant before it enters the compressor.

[0292] The second difference in the 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 bypassing the compressor branch 450. 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. Availablely, the refrigerant in the second refrigeration circuit 410 is essentially provided with free cooling. Clearly, this is advantageous from both a cost and environmental perspective, as energy consumption is significantly reduced compared to operating the compressor branch 450.

[0293] For convenience, the terms "flooded system," "flooded cascade system," etc., refer to the systems of this disclosure, wherein at least one heat exchanger in a low-level refrigeration loop (preferably a low-temperature loop) for condensing a low-level refrigerant (preferably a medium-temperature refrigerant), and preferably all heat exchangers, are flooded evaporators for a high-level refrigerant (preferably a medium-temperature refrigerant). In preferred embodiments according to the invention (including each of systems 1 to 7), the medium-temperature evaporator is also a flooded evaporator. The potential advantages described with reference to cascade refrigeration systems also apply to flooded cascade refrigeration systems: the terminology used to describe flooded and non-flooded cascade refrigeration systems is comparable.

[0294] Another advantage of the flooded cascade refrigeration system according to the invention (including each of systems 1 to 7) may include: reduced energy consumption due to the use of ambient cooling branches (winter operation); improved heat transfer performance in the heat exchanger and evaporator due to their flooded operation; the elimination of the need for a thermostatic expansion valve due to the presence of a pump in the loop; and the ability to manufacture a second refrigeration loop due to the availability of low-cost materials suitable for low-pressure refrigerants.

[0295] In particular, based on the advantages described herein, the present invention (including each of systems 1 to 7) includes a cascade refrigeration system comprising: a plurality of lower-level refrigeration circuits, wherein each lower-level refrigeration circuit includes a first refrigerant comprising, substantially comprising, or comprising: a low-GWP non-flammable (Class A1) refrigerant comprising at least about 50% by weight, or at least about 50% by weight, of R1234yf (specifically including R454A and combinations of R454A with R-454C and / or R455A), having a pressure rating of about 2 horsepower or less. A compressor; and an inter-loop heat exchanger in which the lower-level refrigerant condenses; and an advanced refrigeration circuit comprising an advanced refrigerant and a flooded evaporator, the advanced refrigerant comprising, substantially comprising, or comprising at least about 75% by weight of HFO-1234ze(E) (specifically including R471A and / or R476A and / or R482A), wherein the advanced refrigerant evaporates in the flooded evaporator at a temperature below the condensation temperature of the lower-level refrigerant, wherein the advanced refrigerant evaporates in the inter-loop heat exchanger by absorbing heat from the first refrigerant.

[0296] Flooded Cascade Refrigeration System - Alternative Solution

[0297] The alternatives to the aforementioned reference cascade refrigeration system also apply to flooded cascade refrigeration systems. Other alternatives include removing the ambient cooling branch 451 and / or reversing the flooded system into a direct expansion system. Another change to system 400 (including each of systems 1 to 7) is that the ambient cooling branch 451 can be shortened and simplified so that it bypasses only the compressor 411, rather than the entire compressor branch.

[0298] Advantageously, the use of a shortened ambient cooling branch, i.e., a branch that draws liquid refrigerant from the receiver outlet to the condenser inlet, makes: firstly, a simplified loop, such as the first controllable valve at the inlet of the cooler and receiver pump, no longer necessary; and secondly, a lower-cost loop, due to the reduced number of additional pipes and components for the ambient cooling branch, thus reducing material costs.

[0299] Intake line heat exchanger

[0300] Another possible variation of any system (including each of systems 1 to 7) that forms part of this disclosure is that any number of independently assembled refrigeration circuits may include a suction line heat exchanger (SLHX). More specifically, any one of the lower-level refrigeration circuits 220a, 220b, and 220c in system 200 (including each of systems 1 to 7) may include an SLHX; and any one of the lower-level refrigeration circuits 420a and 420b may include an SLHX. For comparison, Figure 5A The refrigeration circuit 700 without SLHX is shown; while Figure 5B A refrigeration circuit 750 with SLHX 760 is shown.

[0301] Figure 5A The circuit 700 includes a compressor 710, a heat exchanger 720, an expansion valve 730, and an evaporator 740. The compressor 710, heat exchanger 720, expansion valve 730, and evaporator 740 are connected in series in the listed order. In use, the refrigeration circuit 700 functions as described above.

[0302] Figure 5B Circuit 750 has the same components as circuit 700, plus an additional SLHX 760. The SLHX provides a heat exchange interface between the line connecting evaporator 740 and compressor 710 and the line connecting heat exchanger 720 and expansion valve 730. In other words, the SLHX 760 is positioned between the line connecting evaporator 740 and compressor 710 (referred to herein as the vapor line) and the line connecting heat exchanger 720 and expansion valve 730 (referred to herein as the liquid line). In use, the SLHX transfers heat from the liquid line after heat exchanger 720 to the vapor line after evaporator 740. This produces two effects: first, it increases the efficiency of circuit 700; and second, it decreases the efficiency of circuit 700. First, advantageously, on the liquid line side (i.e., the high-pressure side), subcooling of the liquid refrigerant is increased. This is because additional heat is discharged to the liquid expansion side, lowering the temperature of the refrigerant entering expansion valve 730. Following the expansion valve 730 process, this additional subcooling results in a lower inlet mass in the evaporator 740. This increases the enthalpy difference and, consequently, the refrigerant's capacity to absorb heat in the evaporator 740 stage. Therefore, the performance of the evaporator 740 is improved.

[0303] 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 superheat. This results in a higher suction line temperature. Due to the higher suction line temperature to the compressor 710, the enthalpy difference in the compression process increases. This increases the compressor power required to compress the refrigerant. Therefore, this has a detrimental effect on system performance.

[0304] In summary, to determine whether the introduction of SLHX results in an overall beneficial effect, it is necessary to consider both the primary and secondary effects of increasing evaporator capacity and increasing compressor power requirements. Generally, the use of SLHX according to the invention (including each of systems 1 to 7) and, in particular, such systems 200 and 300 herein, produces generally positive and unexpected beneficial effects.

[0305] The advanced refrigeration loop (included in each of systems 1 to 4) may include a second evaporator. The second evaporator may be connected in parallel at the loop interface location.

[0306] Each loop interface location (included in each of systems 1 to 4) may be connected in a series-parallel combination with each other loop interface location. This may mean that if a loop interface location, the first refrigeration circuit, or the first refrigeration unit has a detected fault or blockage, that location, circuit, or unit may be isolated and / or bypassed via a second refrigeration circuit in the event of the fault, preventing the fault from propagating through the system.

[0307] Each loop interface location (included in each of systems 1 to 7) may be connected in series with at least one other loop interface location.

[0308] Each loop interface location in the loop interface locations (included in each of systems 1 to 7) can be connected in series with each other loop interface location in the loop interface locations.

[0309] Each loop interface location (included in each of systems 1 to 7) may be connected in parallel with at least one other loop interface location.

[0310] Each loop interface location in the loop interface locations (included in each of systems 1 to 7) may be connected in parallel with each other loop interface location in the loop interface locations.

[0311] Refrigerant Composition

[0312] HFO-1234ze(E), HFO-1336mzz(E) and HFC-227ea

[0313] This invention provides a refrigerant that may comprise, substantially consist of, or consist of HFO-1234ze(E), HFO-1336mzz(E), and HFC-227ea, and such refrigerants are particularly suitable as advanced refrigerants for preferred cascade systems of this invention (specifically including systems 1 to 7). Lubricant:

[0314] Preferably, the heat transfer composition of the present invention may comprise any of the aforementioned refrigerants and an additional lubricant. The lubricant, when present, is used to lubricate a refrigeration compressor using the refrigerant. Preferably, the lubricant is present in the heat transfer composition in an amount of about 1% to about 50% by weight of the heat transfer composition, more preferably about 10% to about 50% by weight, and most preferably about 30% to about 50% by weight. Available lubricants include alkylbenzenes, esters, polyol esters (“POE”), polyalkylene glycols (“PAG”), polyvinyl ethers (“PVE”), poly-α-olefins (“PAO”), and combinations thereof. Commercially available alkylbenzene lubricants include Zerol 150 (registered trademark). PAG is available in GM Goodwrench Refrigeration Oil and MOPAR-56. Other available esters include phosphate esters, diesters, and fluorinated esters.

[0315] Commercially available POEs include neopentyl glycol dinonanoate (available under 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 defined in the table below:

[0316] characteristic RL32-3MAF RL68H Viscosity at 40°C (ASTM D445), cSt Approximately 31 Approximately 67 Viscosity at 100°C (ASTM D445), cSt Approximately 5.6 Approximately 9.4 Pour point (ASTM D97), ℃ Approximately -40 Approximately -40

[0317] Commercially available PVEs include Idemitsu's polyvinyl ether FVC-32D (registered trademark) and FVC-68D (registered trademark).

[0318] Preferred lubricants include POE and PVE, with POE being more preferred. Of course, different mixtures of different types of lubricants can be used.

[0319] The heat transfer composition of the present invention may consist essentially of or consist of a refrigerant and a lubricant, wherein the lubricant particularly includes each of the preferred lubricants as described above.

[0320] The invention also includes a medium-temperature refrigeration system with two-stage vapor injection compression, and provides particular advantages associated with the medium-temperature refrigeration system, which includes the refrigerant of the invention.

[0321] The invention also includes vending machines and provides particular advantages associated with such vending machines, including vending machines having a suction line / liquid line heat exchanger comprising the refrigerant of the invention.

[0322] The present invention also includes an air source heat pump water heater and provides particular advantages associated with the air source heat pump water heater, including an air source heat pump water heater having an intake / liquid line heat exchanger comprising the refrigerant of the present invention.

[0323] The present invention also includes air conditioning systems (including mobile, residential and commercial air conditioning systems) that incorporate the refrigerant of the present invention, and provides particular advantages associated with such air conditioning systems. Example

[0324] In the following examples, refrigerant compositions were identified as subjects of one or more examples. Each of the refrigerants was subjected to thermodynamic analysis to determine its ability to match the operating characteristics of R-404A in various refrigeration systems. The characteristics of each binary and ternary component pair used in the refrigerants were analyzed using collected experimental data. In the experimental evaluation, the composition of each pair was varied over a series of relative percentages, and the mixture parameters for each pair were regressed to the experimentally obtained data. Known vapor / liquid balance behavior data obtained from the National Institute of Science and Technology (NIST) Reference Fluid Thermodynamics and Transport Properties Database software (Refprop 9.1 NIST Standard Database 23, from April 2016) were used in the examples. The parameters selected for performing the analysis were: the same compressor displacement for all refrigerants, the same operating conditions for all refrigerants, and the same compressor isentropic and volumetric efficiency for all refrigerants. In each example, simulations were performed using measured vapor-liquid balance data. The simulation results for each example are reported.

[0325] Example 1: Performance in a cascade refrigeration system

[0326] Cascade systems are typically used in applications where there is a large temperature difference between the ambient temperature and the chamber temperature (e.g., about 50-80°C, such as about 60-70°C) (e.g., the temperature difference between the air side of the advanced condenser and the air side of the low-level evaporator). For example, cascade systems can be used in supermarket frozen products. In the following embodiments, the baseline cascade system uses CO2 in the low-level stage and R134a in the high-level stage, and the refrigerant combination of the present invention relates to a cascade refrigeration system where the low-level stage is R454A and the refrigerant used in the high-level stage of the system is 1234ze(E), or R471A, or R476A, or 482A.

[0327] The operating conditions are:

[0328] • Condensation temperature = 45℃

[0329] • Advanced condensation temperature - ambient temperature = 10℃

[0330] • Advanced condenser subcooling = 0.0°C (systems with receivers)

[0331] Evaporation temperature = -30℃, corresponding chamber temperature = -18℃

[0332] • Low-stage evaporator superheat = 3.3℃

[0333] • The isentropic efficiency of both high- and low-level compressors is 65%.

[0334] • Volumetric efficiency = 100%

[0335] • Temperature rise in the lower stage of the suction line = 15°C

[0336] • Temperature rise in the advanced inhalation line = 10°C

[0337] • Intermediate heat exchanger CO2 condensation temperatures = 0℃, 5℃ and 10℃

[0338] • Intermediate heat exchanger overheating = 3.3℃

[0339] • Temperature difference in the intermediate heat exchanger = 8℃

[0340] The results are reported in Table E1 below.

[0341] Table E1. Performance in cascade refrigeration systems

[0342] As can be seen from the results reported in Table E1 above, in each case, the refrigerant combination of the present invention (including those defined in systems 1 to 7) produces efficiencies that are as high as or higher than the baseline efficiency.

[0343] Example 2: Miniature Cascade Refrigeration System

[0344] The micro-cascade system combines a conventional medium-temperature DX refrigeration system (with or without a suction line liquid line heat exchanger (SLHX)) that operates using the same refrigerant pairs as defined in Table 1 above. As used herein, the term "medium-temperature DX refrigeration system" refers to a medium-temperature system in which the evaporator is a dry evaporator.

[0345] Available micro-cascade systems are disclosed in our pending U.S. Serial No. 16 / 014,863 and 16 / 015,145, filed June 21, 2018, claiming priority to U.S. Serial No. 62 / 522386, 62 / 522846, 62 / 522851, and 62 / 522860, filed June 21, 2017, all of which are incorporated herein by reference in their entirety.

[0346] Operating conditions:

[0347] Baseline R404A combining MT and LT systems

[0348] · Cooling capacity

[0349] ○Low temperature: 33,000W

[0350] ○Medium temperature: 67,000W

[0351] • Volumetric efficiency: 95% for both MT and LT

[0352] compressor isentropic efficiency

[0353] ○Medium temperature = 70% and low temperature = 67%

[0354] • Condensation temperature: 105℉

[0355] • Medium-temperature evaporation temperature: 20℉

[0356] • Low-temperature evaporation temperature: -20℉

[0357] • Evaporator overheating: 10℉ (both medium and low temperatures)

[0358] • The temperature of the suction line rises (due to heat transfer to the surrounding environment).

[0359] ○ Baseline: Medium temperature: 25℉; Low temperature: 50℉

[0360] ○ SLHX-free cascade / self-contained type: medium temperature: 10℉; low temperature: 25℉

[0361] ○ Cascade / self-contained type with SLHX: Medium temperature: 10℉; Low temperature: 15℉

[0362] SLHX efficiency during use: 65%

[0363] The results are reported in Table E2 below.

[0364] Table E2 - Micro-cascade performance compared to R404A

[0365] As can be seen from the results reported in Table E2 above, in each case, the refrigerant combination of the present invention (including those defined as in systems 1 to 7) produces an efficiency of approximately 110% higher than or equal to the baseline case, while achieving a capacity similar to the baseline. This is an important and unexpected advantage.

[0366] Comparative Example 1 - Centralized Distributed Direct Expansion Supermarket Refrigeration System

[0367] according to Figure 7 The process flow shown provides a centralized distributed supermarket refrigeration system. The system operates using R404A and R448A as refrigerants under a range of environmental conditions from approximately -13°C to approximately 45°C.

[0368]

[0369]

[0370] The results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for COP values) are shown together with the results of Example 5 below. Figure 8 The results of Example C2C (and referred to as I and II), with respect to equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 11 The results of the ambient temperature study are reported in [year]. Figure 11 The values ​​reflect approximate temperatures experienced during operations in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0371] Comparative Example 2 - Direct Expansion Cascade Supermarket Refrigeration System

[0372] according to Figure 9 The process flow shown provides a direct expansion cascade supermarket refrigeration system. The system operates under a range of environmental conditions from approximately -13°C to approximately 45°C, using three different refrigerants (R134a, R515B, and R471A) on the high side (MT system) and R744 on the low side (LT system) under the following conditions.

[0373] Example Name C2A C2B C2C(III) Detailed Implementation unit refrigerant R134a / R744 R515B / R744 R471A / R744 Global warming potential (AR5) [-] <150 <300 <150 Refrigerant charge [kg] 1450 1450 1450 Leakage rate [％] 15％ 15％ 15％ MT evaporation temperature [℃] -6.7 -6.7 -6.7 LT evaporation temperature [℃] -28.9 -28.9 -28.9 LT / MT cooling load [kW] 87 / 138 87 / 138 87 / 138 Evaporator overheating MT / LT [℃] 5.5 5.5 5.5 Inhalation overheating LT [℃] 27.7 27.7 27.7 Inhaled overheated MT [℃] 13.8 13.8 13.8 isentropic efficiency LT [-] 0.6 0.6 0.6 isentropic efficiency MT [-] 0.7 0.7 0.7 Processing temperature cascade HX [K] 5.5 5.5 5.5 Processing temperature condenser [K] 5.5 5.5 5.5 Minimum condensation temperature [℃] 21 21 21

[0374] The results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for COP) are shown together with the results of Example 5 below. Figure 8 The results of Example C2C (and referred to as III), with respect to equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 11 The results of the ambient temperature study are reported in [year]. Figure 11 The values ​​reflect approximate temperatures experienced during operations in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0375] Comparative Example 3 - CO2-Boosted Supermarket Refrigeration System

[0376] according to Figure 10 The process flow shown provides a CO2 booster system using a parallel compression system and a mechanical subcooler in a supermarket refrigeration system. The system operates with R744 and CO2 booster under a range of environmental conditions from approximately -13°C to approximately 45°C.

[0377]

[0378] The results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for COP values) are shown together with the results of Example 5 below. Figure 8 The results of Example C3 (and referred to as V), with respect to equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 11 The results of the ambient temperature study are reported in [year]. Figure 8 The values ​​reflect approximate temperatures experienced during operations in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0379] Comparative Example 4 - R290 Water-Cooled Supermarket Refrigeration System

[0380] The present invention provides an R290 water-cooled supermarket refrigeration system, which operates under a range of environmental conditions from about -13°C to about 45°C, pressurized with R744 and CO2 under the following conditions.

[0381] Example Name C4(VI) Detailed Implementation 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 overheating MT / LT [℃] 5.5 Inhalation overheating LT [℃] 5.5 Inhaled superheated MT [℃] 5.5 isentropic efficiency LT [-] 0.52 isentropic efficiency MT [-] 0.55 Processing temperature cascade HX [K] 5.5 Processing temperature condenser [K] 5.5 Minimum condensation temperature [℃] 15.5

[0382] The results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for COP) are shown together with the results of Example 5 below. Figure 8 The results of Example C4 (and referred to as VI), with respect to equivalent emissions and weighted COP, are shown together with the results of Example 5C below. Figure 11 The results for ambient temperatures are reported, reflecting approximate operating temperatures in Oslo, Norway; Atlanta, USA; and Shanghai, China.

[0383] Example 5 - Micro-cascade supermarket refrigeration system

[0384] According to such Figure 6 The process flow shown describes the operation of the micro-cascade supermarket refrigeration system under a range of environmental conditions from approximately -13°C to approximately 45°C, using R471A in the high-side (MT system) and R454A in the low-side (LT system) under the following conditions.

[0385]

[0386]

[0387] For three sets of environmental conditions, namely 13℃, 30℃, and 45℃, the results of system operation (using R404A in the centralized system of Comparative Example 1 as the baseline for COP values) are presented together with the results of the aforementioned comparative examples. Figure 8 In each group, the first column represents an environment of 13°C, the second column represents an environment of 30°C, and the third column represents an environment of 45°C. These results show that for each of these ambient temperature conditions, the micro-cascade system of the present invention produces the highest COP across all test systems. Similarly, Figure 12 It is noted that, as a function of ambient temperature, the micro-cascade system of the present invention, designated Example 5C, produces significantly better results than all tested systems (except the R744 booster system) at ambient temperatures below approximately 5°C, and significantly better than all systems, including the R744 booster system, at temperatures above 5°C. These results are highly beneficial and unexpected.

[0388] The results of this embodiment in terms of life cycle performance analysis (equivalent emissions and weighted COP), together with the results of the aforementioned comparative examples, are shown in... Figure 11 The emission values ​​are calculated as follows:

[0389] Direct emissions = Refrigerant charge (kg) × ((Annual leakage × Lifespan) + Lifespan loss) × GWP

[0390] Indirect emissions = Annual energy consumption × Lifespan × Emission factor

[0391] from Figure 11 As can be seen from this, it is named Example 5C ( Figure 11 The micro-cascade system of the present invention (IV) produces the highest weighted COP among all test systems under each of the ambient temperature conditions shown. Furthermore, it is named Example 5C (…). Figure 11 The micro-cascade system of the present invention (IV) generates direct and indirect emissions, which even when Figure 9The results also significantly outperform R404A centralized systems, R448A distributed systems, and R477 / R471 A DX cascade systems under the lowest environmental conditions shown, and exhibit the lowest emissions of all systems under environmental conditions represented by both Atlanta, USA and Shanghai, China. These results are both highly beneficial and unexpected. These results also demonstrate that a system with the lowest GWP of a refrigerant does not necessarily result in the lowest emissions. Rather, the total emissions of a 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, the cascade refrigeration system comprising: a. A low-level refrigeration circuit, said low-level refrigeration circuit comprising: The low-grade refrigerant is basically composed of R454A; and compressor; b. An inter-loop heat exchanger in which the lower-grade refrigerant condenses; and c. An advanced refrigeration circuit comprising an advanced refrigerant, the advanced refrigerant: (i) having A1 or A2L flammability; (ii) evaporating at a temperature below the condensation temperature of the lower-level refrigerant; and (iii) comprising at least about 77% by weight of HFO-1234ze(E), wherein the advanced refrigerant evaporates in the inter-circuit heat exchanger by absorbing heat from the refrigerant in the lower-level refrigeration circuit.

2. The cascade refrigeration system according to claim 1, wherein the advanced refrigerant has Class A1 flammability.

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

4. The cascade refrigeration system according to claim 3, wherein the advanced refrigerant is substantially composed of HFO-1234ze(E).

5. The cascade refrigeration system according to claim 3, wherein the advanced refrigerant is substantially composed of R471A.

6. The cascade refrigeration system according to claim 3, wherein the advanced refrigerant is substantially composed of R476A.

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

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

Images