Refrigerant, heat transfer composition, and heat transfer system and method

Abstract

Novel non-flammable refrigerants having a GWP of less than 750 and containing R-32, R-125, R-134a and R-1234yf, novel air conditioning systems (including heat pumps) using such refrigerants, and methods of retrofitting standard single refrigerant vapor compression air conditioning systems using the refrigerants, the standard single refrigerant vapor compression air conditioning system includes, inter alia, a residential heat pump and a residential split direct expansion air conditioning system.

Description

[0001] Cross-references

[0002] The present invention is related to U.S. Provisional Application No. 63 / 421,136 filed on October 31, 2022 and U.S. Provisional Application No. 63 / 412,193 filed on September 30, 2022, claims priority to both of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to high-efficiency, low global warming potential ("low GWP"), non-flammable refrigerants, and to air-conditioning and / or refrigeration systems and methods for providing safe and efficient cooling or heating, including refrigerants and refrigeration / air-conditioning systems and methods with excellent performance as replacements and retrofit solutions for R-410A in air-conditioning, especially R-410A in split direct expansion systems. Background Art

[0004] The refrigeration industry is facing increasing pressure (due to regulatory changes or other reasons) to replace high global warming potential (GWP) refrigerants (such as R410A) with low GWP refrigerants. Under many current regulations and future expected regulations, refrigerants are required to have a GWP of less than 750. The use of refrigerants with a GWP value of less than 750 is particularly important in residential air conditioning systems, because in this application, the potential negative environmental impact of using refrigerants with significantly higher GWP is very large. The high GWP refrigerant R-410A has a GWP of 2088 and is often used in residential air conditioning systems.

[0005] One approach is to use low GWP refrigerants, such as carbon dioxide (R744) and hydrocarbon refrigerants, in typical vapor compression systems. However, such approaches that have been used to date may suffer from significant safety and financial disadvantages, such as: poor system energy efficiency, resulting in increased operating costs; high system complexity, resulting in high initial system costs; low system maintainability and reliability, resulting in high maintenance costs; and high system flammability. Systems that include highly flammable refrigerants according to existing arrangements are particularly disadvantageous because they can result in poor safety levels; may conflict with regulatory code restrictions; and can increase the liability of refrigeration system operators and manufacturers. Safety is a particular concern given that residential air conditioning applications operate in occupied spaces. Therefore, although the refrigerant R410A is non-flammable and can therefore be safely used in residential buildings (since the evaporator is located in the residential building), its significant disadvantage is that it is a high GWP refrigerant, i.e., a GWP much greater than 750. However, in such systems, many low GWP refrigerants that have been proposed to replace R410A have the same unfavorable flammability properties. Therefore, residential air conditioning systems using such proposed flammable fluids run the risk of creating a flammable atmosphere within the residence in the event of a possible leak in the evaporator area.

[0006] EP 2367601 discloses a number of potential refrigerants as replacements for a number of existing refrigerants including R-410A. Among the proposed refrigerants is a blend comprising 50 wt% HFO-1234yf, 40 wt% HFC-32, 5 wt% HFC-125 and 5 wt% HFC-134a, which is disclosed as having a GWP of 519. Although this blend has a significantly lower GWP than R-410A, it has the serious drawback of not being non-flammable, i.e. not being a Class A1 refrigerant. EP2367601 also generally discloses a possible refrigerant comprising 50 wt% HFO-1234yf, 5 wt% HFC-32, 7 wt% HFC-125% and 38 wt% HFC-134a, but this blend is not a possible low GWP replacement for R-410A as described herein because its GWP is significantly higher than 750. Furthermore, the blend is not disclosed for use in specific applications.

[0007] Applicants have come to recognize that there is an ongoing need in the residential air conditioning industry for safe, reliable and sustainable solutions to reduce the use of high GWP refrigerants, particularly Class A1 refrigerants with a GWP of less than 750, and Applicants have met this need by developing new refrigerants and using such refrigerants to provide new air conditioning systems (including heat pumps) that have a similar capacity match to the use of R-410 in standard single-refrigerant vapor compression air conditioning systems (including, in particular, residential heat pumps and residential split direct expansion air conditioning systems that can operate as heat pumps).

[0008] Applicants have discovered that certain refrigerant blends containing carefully selected combinations of components in specific concentrations, as described in detail below, may have an advantageous but unexpected combination of non-flammability, while having excellent heat transfer characteristics, low GWP (e.g., a GWP of less than about 750), low or no toxicity, and chemical stability, among other things. In addition, Applicants have discovered that the refrigerant compositions of the present invention have unique advantages in split-type residential air conditioning systems (including residential heat pumps) in conjunction with methods for retrofitting existing split-type direct expansion residential air conditioning systems (particularly including those having reversing valves that allow the systems to operate in a heating mode) to create secondary loop air conditioning systems therefrom to achieve advantageous results using such new refrigerants.

[0009] As explained in detail herein, the present invention satisfies these and other unmet needs in the art. Summary of the invention

[0010] Applicants have discovered refrigerant compositions, heat transfer compositions containing the refrigerants, heat transfer methods and heat transfer systems (including residential air conditioning methods and systems), and methods of retrofitting existing residential heat pump systems.

[0011] Refrigerants of the present invention include refrigerants having a GWP of less than about 750, classified by ASHRAE as A1 (non-flammable and low toxicity), and preferably having an evaporator glide of about 0°C to less than 5°C.

[0012] The present invention includes a refrigerant comprising at least about 95 weight percent of the following four components based on all refrigerant components:

[0013] (a) from about 50.5 weight percent to about 52.5 weight percent HFO-1234yf,

[0014] (b) about 35.5 to 41 weight percent HFC-134a;

[0015] (c) 2.2 wt% to 5.5 wt% HFC-125; and

[0016] (d) 3.8 to about 8 weight percent HFC-32, wherein the percentages are based on the total amount of (a) to (d).

[0017] The refrigerant according to this paragraph is sometimes referred to herein as Refrigerant 1 for convenience.

[0018] The present invention also includes a refrigerant consisting essentially of:

[0019] from about 50.5 wt % to about 52.5 wt % HFO-1234yf,

[0020] about 35.5 wt % to 41 wt % HFC-134a;

[0021] 2.2 wt% to 5.5 wt% HFC-125; and

[0022] 3.8 wt % to about 8 wt % HFC-32.

[0023] The refrigerant according to this paragraph is sometimes referred to herein as refrigerant 2 for convenience.

[0024] The present invention also includes a refrigerant consisting essentially of:

[0025] 51 to 52.5 wt. % of HFO-1234yf,

[0026] 35.8 to 37.8 wt. % HFC-134a;

[0027] 4.5 to 5.5 wt. % HFC-125; and

[0028] 6 to 8 wt% HFC-32.

[0029] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 3A for convenience.

[0030] The present invention also includes a refrigerant consisting of:

[0031] 51 to 52.5 wt. % of HFO-1234yf,

[0032] 35.8 to 37.8 wt. % HFC-134a;

[0033] 4.5 to 5.5 wt. % HFC-125; and

[0034] 6 to 8 wt% HFC-32.

[0035] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 3B for convenience. The present invention also includes a refrigerant consisting essentially of:

[0036] 52 wt% + 0.5 wt% / - 0.5 wt% HFO-1234yf,

[0037] 39 wt% + 0.5 wt% / - 0.5 wt% HFC-134a;

[0038] 3 wt% + 0.3 wt% / - 0.5 wt% HFC-125; and

[0039] 6 wt% + 0.5 wt% / - 0.3 wt% HFC-32.

[0040] The refrigerant according to this paragraph is sometimes referred to herein as Refrigerant 3B for convenience.

[0041] The present invention also includes a refrigerant consisting of:

[0042] 52 wt% + 0.5 wt% / - 0.5 wt% HFO-1234yf,

[0043] 39 wt% + 0.5 wt% / - 0.5 wt% HFC-134a;

[0044] 3 wt% + 0.3 wt% / - 0.5 wt% HFC-125; and

[0045] 6 wt% + 0.5 wt% / - 0.3 wt% HFC-32.

[0046] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 3C for convenience.

[0047] The present invention also includes a refrigerant consisting essentially of:

[0048] 51.4 wt.% + 0.5 wt.% / - 0.5 wt.% HFO-1234yf,

[0049] 40.4 wt.% + 0.5 wt.% / - 0.5 wt.% HFC-134a;

[0050] 4.1 wt% + 0.3 wt% / - 0.5 wt% HFC-125; and

[0051] 4.1 wt% + 0.5 wt% / - 0.3 wt% HFC-32.

[0052] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 3D for convenience.

[0053] The present invention also includes a refrigerant consisting of:

[0054] 51.4 wt.% + 0.5 wt.% / - 0.5 wt.% HFO-1234yf,

[0055] 40.4 wt.% + 0.5 wt.% / - 0.5 wt.% HFC-134a;

[0056] 4.1 wt% + 0.3 wt% / - 0.5 wt% HFC-125; and

[0057] 4.1 wt% + 0.5 wt% / - 0.3 wt% HFC-32.

[0058] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 3E for convenience.

[0059] The present invention also includes a refrigerant consisting essentially of:

[0060] 51.3 wt.% + 0.5 wt.% / - 0.5 wt.% HFO-1234yf,

[0061] 36 wt% + 0.5 wt% / - 0.5 wt% HFC-134a;

[0062] 5.2 wt% + 0.3 wt% / - 0.5 wt% HFC-125; and

[0063] 7.5 wt% + 0.5 wt% / - 0.3 wt% HFC-32.

[0064] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 3F for convenience. The present invention also includes a refrigerant consisting of:

[0065] 51.3 wt.% + 0.5 wt.% / - 0.5 wt.% HFO-1234yf,

[0066] 36 wt% + 0.5 wt% / - 0.5 wt% HFC-134a;

[0067] 5.2 wt% + 0.3 wt% / - 0.5 wt% HFC-125; and

[0068] 7.5 wt% + 0.5 wt% / - 0.3 wt% HFC-32.

[0069] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 3G for convenience. The present invention also includes a refrigerant consisting essentially of:

[0070] 45 to 47 wt.% HFO-1234yf,

[0071] 36 to 37 wt% HFC-134a;

[0072] 4.5 to 5.5 wt% HFC-125;

[0073] 7 to 8 wt% HFC-32; and

[0074] About 5 wt% HFO-1234ze(E).

[0075] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 4A for convenience. The present invention also includes a refrigerant consisting essentially of:

[0076] about 46 wt% HFO-1234yf,

[0077] about 36.5 wt. % HFC-134a;

[0078] About 5 wt.% HFC-125;

[0079] about 7.5 weight percent HFC-32; and

[0080] About 5 wt% HFO-1234ze(E).

[0081] The refrigerant according to this paragraph is sometimes referred to herein as Refrigerant 4B for convenience. The present invention also includes a refrigerant consisting essentially of:

[0082] 46 wt.% +0.5 wt.% / -0.5 wt.% HFO-1234yf,

[0083] 36.5 wt% + 0.5 wt% / - 0.5 wt% HFC-134a;

[0084] 5 wt% + 0.3 wt% / - 0.5 wt% HFC-125;

[0085] 7.5 wt% + 0.5 wt% / - 0.3 wt% HFC-32; and

[0086] 5 wt% +0.5 wt% / -0.5 wt% HFO-1234ze (E).

[0087] The refrigerant according to this paragraph is sometimes referred to herein as refrigerant 4C for convenience. The present invention also includes a refrigerant consisting of:

[0088] 46 wt.% +0.5 wt.% / -0.5 wt.% HFO-1234yf,

[0089] 36.5 wt% + 0.5 wt% / - 0.5 wt% HFC-134a;

[0090] 5 wt% + 0.3 wt% / - 0.5 wt% HFC-125;

[0091] 7.5 wt% + 0.5 wt% / - 0.3 wt% HFC-32; and

[0092] 5 wt% +0.5 wt% / -0.5 wt% HFO-1234ze (E).

[0093] Refrigerants according to this paragraph are sometimes referred to herein as Refrigerant 4D for convenience.

[0094] The present invention also provides a refrigerant comprising at least about 95 weight percent of the following four components, based on the weight of all refrigerant components:

[0095] (a) from about 50.5 weight percent to about 52.5 weight percent HFO-1234yf,

[0096] (b) about 35.5 to 41 weight percent HFC-134a;

[0097] (c) 2.2 wt% to 5.5 wt% HFC-125; and

[0098] (d) 3.8 wt % to about 8 wt % HFC-32, wherein the percentages are based on the total amount of (a) to (d), provided that the refrigerant has a GWP of less than 750 and is a Class A1 non-flammable refrigerant.

[0099] The refrigerant according to this paragraph is sometimes referred to herein as refrigerant 5A for convenience.

[0100] The present invention also provides a refrigerant comprising at least about 95 weight percent of the following four components, based on the weight of all refrigerant components:

[0101] (a) from about 50.5 weight percent to about 52.5 weight percent HFO-1234yf,

[0102] (b) about 35.5 to 41 weight percent HFC-134a;

[0103] (c) 2.2 wt% to 5.5 wt% HFC-125; and

[0104] (d) 3.8 wt % to about 8 wt % HFC-32, wherein the percentages are based on the total amount of (a) to (d), provided that the refrigerant has a GWP of less than 750, is a Class A1 non-flammable refrigerant, and has an evaporator glide of 0° C. to about 5° C.

[0105] The refrigerant according to this paragraph is sometimes referred to herein as refrigerant 5B for convenience.

[0106] The present invention comprises a secondary circuit air conditioning system for heating and / or cooling indoor air in a residence, comprising:

[0107] (a) A pumped indoor heat transfer circuit comprising:

[0108] An indoor refrigerant having a Class A1 flammability and a GWP of about 750 or less;

[0109] an indoor heat exchanger for exchanging heat with air in the residence; and

[0110] a liquid pump for moving the indoor refrigerant in a liquid phase in the indoor circuit;

[0111] (b) a vapor compression outdoor heat transfer circuit comprising:

[0112] Outdoor refrigerant;

[0113] a compressor for compressing the outdoor refrigerant in a gas phase; and

[0114] an expansion valve for reducing the pressure of the outdoor refrigerant in a liquid phase; and

[0115] An outdoor heat exchanger, the outdoor heat exchanger is used to exchange heat with outdoor air;

[0116] as well as

[0117] (c) An inter-circuit heat exchanger in which the indoor refrigerant exchanges heat with the outdoor refrigerant.

[0118] For convenience, a system according to this paragraph is sometimes referred to herein as heat transfer system 1 .

[0119] The present invention comprises a secondary loop air conditioning system for heating and / or cooling indoor air, comprising:

[0120] (a) A pumped indoor heat transfer circuit comprising:

[0121] a. Based on all refrigerant components, at least about 95% by weight of the following components

[0122] 1. about 50% to about 52.5% by weight of HFO-1234yf,

[0123] 2. from about 35.5 weight percent to about 41 weight percent HFC-134a;

[0124] 3.2.2 to 5.5 wt. % HFC-125; and

[0125] 4.3.8 wt. % to about 8 wt. % HFC-32, wherein the percentages are based on

[0126] The total amount of (1.) to (4.);

[0127] b. an indoor heat exchanger for absorbing heat from the indoor air in a cooling mode and for adding heat to the indoor air in a heating mode;

[0128] c. a liquid pump for moving the indoor refrigerant in a liquid phase to the indoor heat exchanger;

[0129] (b) a vapor compression outdoor heat transfer circuit comprising:

[0130] a. Outdoor refrigerant;

[0131] b. a compressor for compressing the outdoor refrigerant in a gas phase;

[0132] c. an expansion valve for reducing the pressure of the outdoor refrigerant in the liquid phase;

[0133] d. an outdoor heat exchanger for exchanging heat with outdoor air; and

[0134] e. a reversing valve connected to the outlet of the compressor and the outdoor heat exchanger; and

[0135] (c) an inter-circuit heat exchanger in which the indoor refrigerant exchanges heat with the outdoor refrigerant, wherein the reversing valve guides outdoor refrigerant vapor from the compressor to the inter-circuit heat exchanger or the outdoor heat exchanger.

[0136] For convenience, the system according to this paragraph is sometimes referred to herein as heat transfer system 2.

[0137] The present invention comprises a secondary loop air conditioning system for heating and / or cooling indoor air, comprising:

[0138] (a) A pumped indoor heat transfer circuit comprising:

[0139] a. A refrigerant, the refrigerant essentially consisting of:

[0140] 1. about 49% by weight of difluoromethane (HFC-32),

[0141] 2. about 11.5 weight percent pentafluoroethane (HFC-125), and

[0142] 3. about 39.5% by weight of trifluoroiodomethane (CF3I);

[0143] b. an indoor heat exchanger for absorbing heat from the indoor air in a cooling mode and for adding heat to the indoor air in a heating mode;

[0144] c. a liquid pump for moving the indoor refrigerant in a liquid phase to the indoor heat exchanger;

[0145] (b) a vapor compression outdoor heat transfer circuit comprising:

[0146] a. Outdoor refrigerant;

[0147] b. a compressor for compressing the outdoor refrigerant in a gas phase;

[0148] c. an expansion valve for reducing the pressure of the outdoor refrigerant in the liquid phase;

[0149] d. an outdoor heat exchanger for exchanging heat with outdoor air; and

[0150] e. a reversing valve connected to the outlet of the compressor and the outdoor heat exchanger; and

[0151] (c) an inter-circuit heat exchanger in which the indoor refrigerant exchanges heat with the outdoor refrigerant, wherein the reversing valve guides outdoor refrigerant vapor from the compressor to the inter-circuit heat exchanger or the outdoor heat exchanger.

[0152] For convenience, the system according to this paragraph is sometimes referred to herein as heat transfer system 3.

[0153] The present invention includes a method of providing heating and / or cooling to indoor air in a residence, comprising:

[0154] (a) providing an indoor refrigerant, the indoor refrigerant comprising at least about 95 weight percent of the following components, based on all refrigerant components:

[0155] a. about 50.5 wt % to about 52.5 wt % HFO-1234yf,

[0156] b. about 35.5 wt % to 41 wt % HFC-134a;

[0157] c. 2.2 wt% to 5.5 wt% HFC-125; and

[0158] d. 3.8 wt % to about 8 wt % HFC-32, wherein the percentages are based on the total amount of a. to d.; and

[0159] (b) heating or cooling the indoor air by exchanging heat with the indoor refrigerant.

[0160] The method according to this paragraph is sometimes referred to herein as Heat Transfer Method 1 for convenience.

[0161] The present invention also includes a method of providing heating and / or cooling to indoor air in a residence, comprising:

[0162] (a) providing a pumped indoor heat transfer circuit, the pumped indoor heat transfer circuit comprising:

[0163] a. an indoor refrigerant having a Class A1 flammability and having a GWP of about 750 or less;

[0164] b. an indoor heat exchanger for exchanging heat with air in a residence; and

[0165] c. a liquid pump for moving the indoor refrigerant in a liquid phase in the indoor circuit;

[0166] (b) providing a vapor compression outdoor heat transfer circuit, the vapor compression outdoor heat transfer circuit comprising:

[0167] a. Outdoor refrigerant;

[0168] b. a compressor for compressing the outdoor refrigerant in a gas phase; and

[0169] c. an expansion valve for reducing the pressure of the outdoor refrigerant in the liquid phase; and

[0170] d. an outdoor heat exchanger, which is used to exchange heat with outdoor air;

[0171] (c) exchanging heat between the indoor refrigerant and the outdoor refrigerant.

[0172] The method according to this paragraph is sometimes referred to herein as Heat Transfer Method 2 for convenience.

[0173] The present invention includes a method of providing heating and / or cooling to indoor air in a residence, comprising:

[0174] (a) providing a pumped indoor heat transfer circuit, the pumped indoor heat transfer circuit comprising:

[0175] a. A refrigerant, the refrigerant essentially consisting of:

[0176] 1. about 49% by weight of difluoromethane (HFC-32),

[0177] 2. about 11.5 weight percent pentafluoroethane (HFC-125), and

[0178] 3. about 39.5% by weight of trifluoroiodomethane (CF3I);

[0179] b. an indoor heat exchanger for absorbing heat from the indoor air in a cooling mode and for adding heat to the indoor air in a heating mode;

[0180] c. a liquid pump for moving the indoor refrigerant in a liquid phase to the indoor heat exchanger;

[0181] (b) heating or cooling the indoor air by exchanging heat with the indoor refrigerant.

[0182] For convenience, the system according to this paragraph is sometimes referred to herein as heat transfer method 3.

[0183] The present invention includes a method for retrofitting an existing residential heat pump air conditioning system, the existing residential heat pump air conditioning system using a vapor compression cycle with R410a as a refrigerant and a reversing valve to provide heating or cooling to indoor air in a residence, the method comprising:

[0184] (a) providing an existing heat pump system, the heat pump system comprising:

[0185] a.Compressor;

[0186] b. an outdoor heat exchanger for exchanging heat between outdoor air and the R410A refrigerant;

[0187] c. an indoor heat exchanger for exchanging heat between indoor air and the R410A refrigerant;

[0188] d. a reversing valve connected to the inlet and outlet of the compressor, and each of the outdoor heat exchanger and the indoor heat exchanger;

[0189] e. an expansion valve connected between the outdoor heat exchanger and the indoor heat exchanger;

[0190] (b) disconnecting the indoor heat exchanger from the expansion valve and the reversing valve;

[0191] (c) providing an inter-circuit heat exchanger, connecting the inter-circuit heat exchanger to the expansion valve and the reversing valve to provide a flow path for the R410A refrigerant to pass therethrough;

[0192] (d) creating a pumped secondary refrigerant circuit including the indoor heat exchanger, a liquid pump, and the inter-circuit heat exchanger by connecting the pump to each of the inter-circuit heat exchanger and the indoor coil; and

[0193] (e) providing an indoor refrigerant in the pumped secondary loop, the indoor refrigerant comprising at least about 95 weight percent of the following components, based on all refrigerant components:

[0194] a. about 50.5 wt % to about 52.5 wt % HFO-1234yf,

[0195] b. about 35.5 wt % to 41 wt % HFC-134a;

[0196] c. 2.2 wt% to 5.5 wt% HFC-125; and

[0197] d. 3.8 wt % to about 8 wt % HFC-32, wherein the percentages are based on the total amount of a. to d.

[0198] The method according to this paragraph is sometimes referred to herein as Modified Method 1A for convenience.

[0199] The present invention includes a method for retrofitting an existing residential heat pump air conditioning system, the existing residential heat pump air conditioning system using a vapor compression cycle with R410a as a refrigerant and a reversing valve to provide heating or cooling to indoor air in a residence, the method comprising:

[0200] (a) providing an existing heat pump system, the heat pump system comprising:

[0201] a.Compressor;

[0202] b. an outdoor heat exchanger for exchanging heat between outdoor air and the R410A refrigerant;

[0203] c. an indoor heat exchanger for exchanging heat between indoor air and the R410A refrigerant;

[0204] d. a reversing valve connected to the inlet and outlet of the compressor, and each of the outdoor heat exchanger and the indoor heat exchanger;

[0205] e. a fluid flow line connecting the expansion valve to the indoor heat exchanger and connecting the indoor heat exchanger to the reversing valve;

[0206] (b) disconnecting the indoor heat exchanger from the expansion valve and the reversing valve;

[0207] (c) providing an inter-circuit heat exchanger, connecting the inter-circuit heat exchanger to the expansion valve and the reversing valve using a substantial portion of the fluid flow line to provide a flow path for the R410A refrigerant therethrough;

[0208] (d) creating a pumped secondary refrigerant circuit including the indoor heat exchanger, a liquid pump, and the inter-circuit heat exchanger by connecting the pump to each of the inter-circuit heat exchanger and the indoor coil; and

[0209] (e) providing an indoor refrigerant in the pumped secondary loop, the indoor refrigerant comprising at least about 95 weight percent of the following components, based on all refrigerant components:

[0210] a. about 50.5 wt % to about 52.5 wt % HFO-1234yf,

[0211] b. about 35.5 wt % to 41 wt % HFC-134a;

[0212] c. 2.2 wt % to about 5.5 wt % HFC-125; and

[0213] d. 3.8 wt % to about 8 wt % HFC-32, wherein the percentages are based on the total amount of a. to d.

[0214] The method according to this paragraph is sometimes referred to herein as Modified Method 1B for convenience.

[0215] The present invention includes a method for retrofitting an existing residential heat pump air conditioning system, the existing residential heat pump air conditioning system using a vapor compression cycle with R410a as a refrigerant and a reversing valve to provide heating or cooling to indoor air in a residence, the method comprising:

[0216] (f) providing an existing heat pump system, the heat pump system comprising:

[0217] a.Compressor;

[0218] b. an outdoor heat exchanger for exchanging heat between outdoor air and the R410A refrigerant;

[0219] c. an indoor heat exchanger for exchanging heat between indoor air and the R410A refrigerant;

[0220] d. a reversing valve connected to the inlet and outlet of the compressor, and each of the outdoor heat exchanger and the indoor heat exchanger;

[0221] e. an expansion valve connected between the outdoor heat exchanger and the indoor heat exchanger;

[0222] (g) disconnecting the indoor heat exchanger from the expansion valve and the reversing valve;

[0223] (h) providing an inter-circuit heat exchanger, connecting the inter-circuit heat exchanger to the expansion valve and the reversing valve to provide a flow path for the R410A refrigerant to pass therethrough;

[0224] (i) creating a pumped secondary refrigerant circuit including the indoor heat exchanger, a liquid pump, and the inter-circuit heat exchanger by connecting the pump to each of the inter-circuit heat exchanger and the indoor coil; and

[0225] (j) providing an indoor refrigerant in the pumped secondary loop, the indoor refrigerant comprising at least about 95 weight percent of the following components, based on all refrigerant components:

[0226] a. about 49% by weight of HFC-32,

[0227] b. about 11.5 wt % HFC-125; and

[0228] c. About 39.5 wt% CF3I.

[0229] The method according to this paragraph is sometimes referred to herein as Modification Method 2 for convenience.

[0230] The present invention includes a method for retrofitting an existing residential heat pump air conditioning system, the existing residential heat pump air conditioning system using a vapor compression cycle with R410a as a refrigerant and a reversing valve to provide heating or cooling to indoor air in a residence, the method comprising:

[0231] (a) An existing heat pump system is provided, the heat pump system comprising:

[0232] a.Compressor;

[0233] b. an outdoor heat exchanger for exchanging heat between outdoor air and the R410A refrigerant;

[0234] c. an indoor heat exchanger for exchanging heat between indoor air and the R410A refrigerant;

[0235] d. a reversing valve connected to the inlet and outlet of the compressor, and each of the outdoor heat exchanger and the indoor heat exchanger;

[0236] e. an expansion valve connected between the outdoor heat exchanger and the indoor heat exchanger;

[0237] (b) disconnecting the indoor heat exchanger from the expansion valve and the reversing valve;

[0238] (c) providing an inter-circuit heat exchanger, connecting the inter-circuit heat exchanger to the expansion valve and the reversing valve to provide a flow path for the R410A refrigerant to pass therethrough;

[0239] (d) creating a pumped secondary refrigerant circuit including the indoor heat exchanger, a liquid pump, and the inter-circuit heat exchanger by connecting the pump to each of the inter-circuit heat exchanger and the indoor coil; and

[0240] (e) providing an indoor refrigerant having Class A1 flammability and having a GWP of about 750 or less in the pumped secondary circuit.

[0241] The method according to this paragraph is sometimes referred to herein as Modified Method 2A for convenience.

[0242] The present invention includes a method for retrofitting an existing residential heat pump air conditioning system, the existing residential heat pump air conditioning system using a vapor compression cycle with R410a as a refrigerant and a reversing valve to provide heating or cooling to indoor air in a residence, the method comprising:

[0243] (a) providing an existing heat pump system, the heat pump system comprising:

[0244] a.Compressor;

[0245] b. an outdoor heat exchanger for exchanging heat between outdoor air and the R410A refrigerant;

[0246] c. an indoor heat exchanger for exchanging heat between indoor air and the R410A refrigerant;

[0247] d. a reversing valve connected to the inlet and outlet of the compressor, and each of the outdoor heat exchanger and the indoor heat exchanger;

[0248] e. an expansion valve connected between the outdoor heat exchanger and the indoor heat exchanger;

[0249] f. a fluid flow line connecting the expansion valve to the indoor heat exchanger and connecting the indoor heat exchanger to the reversing valve;

[0250] (b) disconnecting the indoor heat exchanger from the expansion valve and the reversing valve;

[0251] (c) providing an inter-circuit heat exchanger, connecting the inter-circuit heat exchanger to the expansion valve and the reversing valve using a substantial portion of the fluid flow line to provide a flow path for the R410A refrigerant therethrough;

[0252] (d) creating a pumped secondary refrigerant circuit including the indoor heat exchanger, a liquid pump, and the inter-circuit heat exchanger by connecting the pump to each of the inter-circuit heat exchanger and the indoor coil; and

[0253] (e) providing an indoor refrigerant having Class A1 flammability and having a GWP of about 750 or less in the pumped secondary circuit.

[0254] The method according to this paragraph is sometimes referred to herein as Modified Method 2B for convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0255] Figure 1A is a schematic diagram of an exemplary residential air conditioning system of the present invention in cooling mode.

[0256] Figure 1B is a schematic diagram of an exemplary residential air conditioning system of the present invention in heating mode.

[0257] Figure 2A is a schematic diagram of a typical residential heat pump system operating in cooling mode, the system being subjected to the retrofit method of the present invention.

[0258] Figure 2B is a schematic diagram of a typical residential heat pump system operating in heating mode, the system being subjected to the retrofit method of the present invention. DETAILED DESCRIPTION

[0259] definition:

[0260] The phrase "coefficient of performance" (hereinafter referred to as "COP") is a generally recognized measure of refrigerant system performance, and is particularly useful for representing the relative thermodynamic efficiency of a refrigerant system in a specific heating or cooling cycle involving refrigerant evaporation or condensation. In refrigeration engineering, the term represents the ratio of available refrigeration or cooling capacity to the energy applied by the compressor when compressing vapor, thus representing the ability of a given compressor to pump heat for a given volume flow of heat transfer fluid (such as a refrigerant). In other words, given a specific compressor, a refrigerant with a higher COP will deliver more cooling or heating power. A method for estimating the COP of a refrigerant in a system under specific operating conditions is to estimate from the thermodynamic properties of a refrigerant using standard refrigeration cycle analysis techniques (see, for example, RC Downing, "FLUOROCARBONREFRIGERANTS HANDBOOK", Chapter 3, Prentice-Hall, 1988, which is incorporated herein by reference in its entirety). The term "capacity" is the amount of cooling (in BTU / hour) provided by a refrigerant in a refrigeration system. This is determined experimentally by multiplying the enthalpy change (in BTU / lb) of the refrigerant as it passes through the evaporator by the mass flow rate of the refrigerant. The enthalpy can be determined by measurements of the pressure and temperature of the refrigerant. The capacity of a refrigeration system relates to the ability to keep an area cooled at a specific temperature. The capacity of a refrigerant represents the amount of cooling or heating it provides, and provides some measure of the ability of the compressor to pump heat for a given volume flow of refrigerant. In other words, given a specific compressor, a refrigerant with a higher capacity will deliver more cooling or heating power.

[0261] The phrase "global warming potential" (hereinafter "GWP") was created to allow comparison of the global warming impact of different gases. GWP compares the amount of heat trapped by a certain mass of a gas over a specific time period to the amount of heat trapped by a similar mass of carbon dioxide. Carbon dioxide was selected by the Intergovernmental Panel on Climate Change (IPCC) as the reference gas and its GWP was taken to be 1. The greater the GWP, the more a given gas warms the Earth compared to CO2 over that time period. As used herein, the term GWP refers to the global warming potential of a gas as measured by the 2014 Climate Change Climate Change Index. 1 The GWP values ​​measured in the IPCC Fourth Assessment Report (referred to herein and abbreviated as AR4).

[0262] The term "nonflammable" refers to a compound or composition that is determined to be nonflammable according to ASTM Standard E-681-2009 Standard Test Method for Flammable Concentration Limits of Chemicals (Vapor and Gases) (as various standards existed prior to the filing date of this application), which is incorporated herein by reference in its entirety ("Nonflammability Test") under the conditions described in ASHRAE Standard 34-2016, Designation and Safety Classification of Refrigerants, and Appendix B1 of ASHRAE Standard 34-2016. Flammability is defined as the ability of a composition to ignite and / or propagate a flame. Under this test, flammability is determined by measuring the flame angle. Nonflammable substances are classified as Class "1" by the definition of conditions and equipment in the ASHRAE Standard 34-2016, Designation and Safety Classification of Refrigerants test procedure, and using the current method ASTM E681-09 Annex A1 (as each standard existed as of the filing date of this application).

[0264] As used herein, the term "evaporator glide" refers to the difference between the saturation temperature of the refrigerant at the evaporator inlet and the dew point of the refrigerant at the evaporator outlet, assuming that the pressure at the evaporator outlet is the same as the pressure at the inlet. As used herein, the phrase "saturation temperature" refers to the temperature at which a liquid refrigerant boils into vapor at a given pressure.

[0265] As used herein, the phrase "non-toxic or low toxicity" means that the composition is classified as "A" by ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification, and is described in ASHRAE Standard 34-2016 Annex B1 (such as various standards existed before the filing date of this application). Non-flammable and low toxic materials are classified as "A1" by ASHRAE Standard 34-2016 Nomenclature and Refrigerant Safety Classification, and are described in ASHRAE Standard 34-2016 Annex B1 (such as various standards existed before the filing date of this application).

[0266] The term "superheat" or simply "superheat" refers to the temperature of the refrigerant at the evaporator outlet rising above the saturated vapor temperature (or dew point temperature) of the refrigerant.

[0267] As used herein, the term "E-1,3,3,3-tetrafluoropropene" refers to the trans isomer of HFO-1234ze and is abbreviated as HFO-1234ze(E).

[0268] As used herein, the term "2,3,3,3-tetrafluoropropene" is abbreviated as HFO-1234yf.

[0269] As used herein, the term "1,1,1,2-tetrafluoroethane" is known in the industry by the abbreviation HFC-134a and is abbreviated herein as HFC-134a. As used herein, the term "pentafluoroethane" is known in the industry by the abbreviation HFC-125 and is abbreviated herein as HFC-125.

[0270] As used herein, the term "difluoromethane" is known in the industry by the abbreviation HFC-32 and is abbreviated herein as HFC-32.

[0271] As used herein, the term "chlorodifluoromethane" is known in the industry by the abbreviation R-22 and is abbreviated herein as R-22.

[0272] As used herein, the term "trifluoroiodomethane" refers to CF3I and is abbreviated as CF3I.

[0273] As used herein, the term "residential air conditioning" refers to a refrigeration system that operates with a heat exchanger that absorbs heat from or adds heat to indoor air in a structure occupied by humans.

[0274] As used herein, the term "split direct expansion air conditioning system" means an air conditioning system that operates with an indoor unit located inside a residence and including a heat exchanger that absorbs heat from or adds heat to indoor air in a structure in which humans reside, and an outdoor unit that includes a heat exchanger located outside the residence that releases heat to or absorbs heat from outdoor air.

[0275] As used herein, the term "secondary loop air conditioning system" refers to an air conditioning system having an internal refrigeration circuit that uses an indoor (or secondary) refrigerant to heat and / or cool the interior air and an external refrigeration circuit that uses an outdoor (or primary) refrigerant that is different from the indoor refrigerant and discharges heat to the outdoor air or absorbs heat from the outdoor air.

[0276] As used herein, the term "suction line" used in connection with a secondary loop air conditioning system refers to the refrigerant flow path from the outlet of the intermediate heat exchanger to the inlet of the compressor.

[0277] As used herein, the term "liquid line" used in connection with a secondary loop air conditioning system refers to the refrigerant flow path from the outlet of the condenser to the inlet of the intermediate heat exchanger.

[0278] As used herein, the term "R410A" refers to a refrigerant designated by ASHRAE as 410A, which is composed of 50%+2% / -2% R-32 and 50%+2% / -2% HFC-125.

[0279] As used herein, the term "R454B" refers to a refrigerant designated by ASHRAE as 454B, which is composed of 69.9% + 2% / - 2% R-32 and 31.1% + 2% / - 2% HFC-1234yf.

[0280] As used herein, the term "R466A" refers to a refrigerant designated by ASHRAE as 466A, which consists of 49%+0.5% / -2.0% R-32, 11.5%+2.0% / -0.5% HFC-125, and 39.5%+2.0% / -0.5% CF3I.

[0281] As used herein, the term "about" in connection with an amount expressed as a weight percent means that the amount of the component may vary by + / - 2 weight percent.

[0282] Refrigerants and heat transfer compositions :

[0283] Applicants have discovered that the refrigerants of the present invention (including each of Refrigerants 1 to 5 as described herein) are unexpectedly capable of providing an exceptionally advantageous set of properties, including: excellent heat transfer properties, acceptable toxicity and non-flammability (i.e., Class 1A), zero or near zero ozone depletion potential ("ODP"), and preferably relatively low evaporator glide, i.e., from 0°C to less than 5°C.

[0284] As used herein, reference to a numbered refrigerant, system, or method, or a group of such numbered refrigerants, systems, and methods, which have been defined herein, means each such numbering system, including each system having a number within the group, including any suffixed numbering systems. For example, reference to refrigerant 4 includes reference to each of refrigerants 4A, 4B, 4C, and 4D.

[0285] The unique advantage of the refrigerants of the present invention (specifically including each of refrigerants 1 to 5) is that they are all non-flammable and have acceptable toxicity, that is, each is a Class A1 refrigerant. Those skilled in the art will understand that the flammability of a refrigerant may be a property considered in certain important heat transfer applications, and a refrigerant classified as Class A1 may generally be superior to a non-Class A1 refrigerant. Therefore, the art desires to provide a refrigerant composition that can be used as a replacement for existing non-flammable refrigerants (including R410A and R-22) with excellent heat transfer properties, acceptable toxicity, and zero or near-zero ODP. This combination of desired advantages is achieved by the refrigerants of the present invention (specifically including each of refrigerants 1 to 5), and further in combination with the use of such refrigerants in the systems of the present invention (including systems 1 and 2) and in the methods of the present invention (including methods 1 and 2).

[0286] Applicants have discovered that the refrigerant compositions of the present invention, including each of Refrigerants 1 to 5, achieve a combination of properties that are difficult to achieve, particularly including a GWP of 750 or less and Class A1 flammability.

[0287] In addition, the refrigerant composition of the present invention (including each of Refrigerants 1 to 5) has an ODP of zero or close to zero. Therefore, the composition of the present invention has an ODP of no greater than 0.02, and more preferably zero.

[0288] In addition, the refrigerant compositions of the present invention, including each of Refrigerants 1 to 5, have acceptable toxicity, and preferably have an OEL greater than about 400. As will be appreciated by those skilled in the art, a non-flammable refrigerant having an OEL greater than about 400 is advantageous because it results in the refrigerant being classified as the desired ASHRAE Standard 34 Class A.

[0289] Preferred refrigerant compositions of the present invention, including each of Refrigerants 1 to 5, have both acceptable toxicity and non-flammability and are therefore Class A1 refrigerants according to ASHRAE Standard 34. Applicants have discovered that heat transfer compositions of the present invention, including heat transfer compositions including each of Refrigerants 1 to 5 as described herein, can provide an exceptionally advantageous and unexpected combination of properties, including good heat transfer properties, acceptable toxicity, non-flammability, zero or near zero ozone depletion potential ("ODP"), and chemical stability under conditions of use, including within the operating temperature range for use in air conditioning, particularly residential air conditioning.

[0290] Method, use and system

[0291] system

[0292] The present invention includes all types of heat transfer systems that include the refrigerant of the present invention, including each of Refrigerants 1 to 5. The heat transfer system as described in this paragraph is sometimes referred to as heat transfer system 3 for convenience.

[0293] The present invention also includes and provides unique advantages associated with secondary loop air conditioning systems that include a refrigerant of the present invention in the indoor loop of such a system, including each of refrigerants 1 to 5. The heat transfer system as described in this paragraph is sometimes referred to as heat transfer system 4 for convenience.

[0294] The present invention also includes and provides unique advantages associated with secondary circuit residential air conditioning systems that include a refrigerant of the present invention in the indoor circuit of such a system, including each of Refrigerants 1 to 5. The heat transfer system as described in this paragraph is sometimes referred to as heat transfer system 5 for convenience.

[0295] Methods - Heat Transfer Methods

[0296] The present invention includes all types of heat transfer methods that include the refrigerant of the present invention, including each of Refrigerants 1 to 5. The heat transfer method as described in this paragraph is sometimes referred to as Heat Transfer Method 3 for convenience.

[0297] The present invention also includes a heat transfer method implemented in a secondary loop air conditioning system and provides unique advantages associated with a heat transfer method implemented in a secondary loop air conditioning system that includes a refrigerant of the present invention in the indoor loop of such a system, including each of Refrigerants 1 to 5. The heat transfer method as described in this paragraph is sometimes referred to as heat transfer method 4 for convenience.

[0298] The present invention also includes and provides unique advantages associated with heat transfer methods implemented in secondary loop residential air conditioning systems that include a refrigerant of the present invention, including each of Refrigerants 1 to 5, in the indoor loop of such systems. The heat transfer system as described in this paragraph is sometimes referred to as heat transfer method 5 for convenience.

[0299] Method – Transformation Method

[0300] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system. Before the existing system is modified according to the present invention, the same existing high GWP refrigerant, including R410A or R-22, is used in both the indoor unit and the outdoor unit. According to the modification method of the present invention, the existing system is improved so that the secondary circuit (indoor) system uses the refrigerant of the present invention (including each of refrigerants 1 to 5) to replace the existing refrigerant previously used. The modification method as described in this paragraph is sometimes referred to as modification method 3 for convenience.

[0301] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, which includes a reversing valve that allows the system to operate in a heating mode and a cooling mode. Before the existing system is modified by the present invention, it uses existing high GWP refrigerants in the indoor unit and the outdoor unit, including R410A or R-22, to produce a secondary circuit air conditioning system that can operate in a heating mode or a cooling mode. According to the modification method of the present invention, the existing system is improved so that the refrigerant in the indoor (secondary) circuit is the refrigerant of the present invention, including each of refrigerants 1 to 5. The modification method as described in this paragraph is sometimes referred to as modification method 4 for convenience.

[0302] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, which includes an inter-unit refrigerant pipe between an indoor unit and an outdoor unit, a reversing valve that allows the system to operate in a heating mode, and an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is modified without replacing a major portion of the inter-unit pipe to produce a secondary circuit system, in which the refrigerant in the indoor (secondary) circuit is the refrigerant of the present invention, including each of refrigerants 1 to 5. The modification method as described in this paragraph is sometimes referred to as modification method 5 for convenience.

[0303] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, which includes an inter-unit refrigerant pipe between an indoor unit and an outdoor unit, a reversing valve that allows the system to operate in a heating mode and in a cooling mode, and an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is modified without replacing a major part of the inter-unit pipe to produce a secondary circuit system, in which the refrigerant in the secondary circuit is the refrigerant of the present invention, including each of refrigerants 1 to 5. The modification method as described in this paragraph is sometimes referred to as modification method 6 for convenience.

[0304] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, which includes an inter-unit refrigerant pipe between an indoor unit and an outdoor unit, a reversing valve that allows the system to operate in a heating mode or a cooling mode, and an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is improved without replacing a major portion of the inter-unit pipe to produce a secondary circuit system, in which: (i) the refrigerant in the secondary circuit is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) the saturation temperature drop in the suction line is 2°F or less; and (iii) the saturation temperature drop in the liquid line is 1°F or less. The modification method as described in this paragraph is sometimes referred to as modification method 7A for convenience.

[0305] The present invention includes a modification method based on an existing split direct expansion vapor compression air conditioning system, which includes a reversing valve that allows the system to operate in a heating mode or a cooling mode, and an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is improved to produce a secondary loop system, in which: (i) the refrigerant in the secondary loop is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) the capacity is at least about 90% of the capacity of the existing split direct expansion vapor compression air conditioning system; and (iii) the COP is at least about 90% of the COP of the existing split direct expansion vapor compression air conditioning system. The modification method as described in this paragraph is sometimes referred to as modification method 7B for convenience.

[0306] The present invention includes a modification method based on an existing split direct expansion vapor compression air conditioning system, which includes an inter-unit refrigerant pipe between an indoor unit and an outdoor unit, a reversing valve that allows the system to operate in a heating mode or a cooling mode, and an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is improved without replacing a major portion of the inter-unit pipe to produce a secondary loop system, in which: (i) the refrigerant in the secondary loop is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) the capacity is at least about 90% of the capacity of the existing split direct expansion vapor compression air conditioning system; (iii) the COP is at least about 90% of the COP of the existing split direct expansion vapor compression air conditioning system; (iv) the saturated temperature drop in the suction line is 2°F or less; and (v) the saturated temperature drop in the liquid line is 1°F or less. The modification method as described in this paragraph is sometimes referred to as modification method 7C for convenience.

[0307] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, which includes: (i) a reversing valve that allows the system to operate in a heating mode or a cooling mode; (ii) an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22; (iii) an existing compressor; and (iv) an existing outdoor heat exchanger. According to the modification method of the present invention, the existing system is improved so that: (i) the refrigerant in the secondary circuit is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) the displacement of the compressor in the outdoor unit is about 4% to about 96% of the displacement of the compressor in the existing system; and (iii) the heat transfer surface of the outdoor heat exchanger is about 16% to about 68% of the area of ​​the outdoor heat exchanger in the existing system. The modification method as described in this paragraph is sometimes referred to as modification method 7D for convenience.

[0308] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, the air conditioning system including: (i) inter-unit refrigerant piping between an indoor unit and an outdoor unit; (ii) a reversing valve that allows the system to operate in a heating mode; (iii) existing high GWP refrigerants in the indoor unit and the outdoor unit, including R410A or R-22; (iv) an existing compressor; and (v) an existing outdoor heat exchanger. According to the modification method of the present invention, the existing system is modified without replacing a major portion of the inter-unit piping to produce a secondary loop system in which: (i) the refrigerant in the secondary loop is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) the displacement of the compressor in the outdoor unit is about 4% to about 96% of the displacement of the compressor in the existing system; (iii) the heat transfer surface of the outdoor heat exchanger is about 16% to about 68% of the area of ​​the outdoor heat exchanger in the existing system; (iv) the saturation temperature drop in the suction line is 2°F or less; and (v) the saturation temperature drop in the liquid line is 1°F or less. The modification method as described in this paragraph is sometimes referred to as modification method 7E for convenience.

[0309] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, which includes an inter-unit refrigerant pipe between an indoor unit and an outdoor unit, a reversing valve that allows the system to operate in a heating mode or a cooling mode, an expansion valve in the outdoor unit, and an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is improved without replacing a major portion of the inter-unit pipe to produce a secondary circuit system in which: (i) the refrigerant in the secondary circuit is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) a replacement expansion valve is introduced into the system, working in the outdoor circuit; (iii) the saturation temperature drop in the suction line is 2°F or less; and (iv) the saturation temperature drop in the liquid line is 1°F or less. The modification method as described in this paragraph is sometimes referred to as modification method 7A for convenience.

[0310] The present invention includes a modification method based on an existing split direct expansion vapor compression air conditioning system, which includes a reversing valve that allows the system to operate in a heating mode or a cooling mode, an expansion valve in an outdoor unit, and existing high GWP refrigerants in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is modified to produce a secondary loop system, in which: (i) the refrigerant in the secondary loop is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) a replacement expansion valve is introduced into the system, working in the outdoor loop; (iii) the capacity is at least about 90% of the capacity of the existing split direct expansion vapor compression air conditioning system; and (iv) the COP is at least about 90% of the COP of the existing split direct expansion vapor compression air conditioning system. The modification method as described in this paragraph is sometimes referred to as modification method 7B for convenience.

[0311] The present invention includes a modification method based on an existing split direct expansion vapor compression air conditioning system, which includes an inter-unit refrigerant pipe between an indoor unit and an outdoor unit, a reversing valve that allows the system to operate in a heating mode or a cooling mode, an expansion valve in the outdoor unit, and an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22. According to the modification method of the present invention, the existing system is improved without replacing a major portion of the inter-unit pipe to produce a secondary loop system, in which: (i) the refrigerant in the secondary loop is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) a replacement expansion valve is introduced into the system and works in the outdoor loop; (iii) the capacity is at least about 90% of the capacity of the existing split direct expansion vapor compression air conditioning system; (iv) the COP is at least about 90% of the COP of the existing split direct expansion vapor compression air conditioning system; (v) the saturation temperature drop in the suction line is 2°F or less; and (vi) the saturation temperature drop in the liquid line is 1°F or less. The modification method as described in this paragraph is sometimes referred to as modification method 7C for convenience.

[0312] The present invention includes a modification method based on an existing split-type direct expansion vapor compression air conditioning system, which includes: (i) a reversing valve that allows the system to operate in a heating mode or a cooling mode; (ii) an expansion valve in the outdoor unit, (iii) an existing high GWP refrigerant in the indoor unit and the outdoor unit, including R410A or R-22; (iv) an existing compressor; and (v) an existing outdoor heat exchanger. According to the modification method of the present invention, the existing system is improved so that: (i) the refrigerant in the secondary circuit is a refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) a replacement expansion valve is introduced into the system, working in the outdoor circuit; (iii) the displacement of the compressor in the outdoor unit is about 4% to about 96% of the displacement of the compressor in the existing system; and (iv) the heat transfer surface of the outdoor heat exchanger is about 16% to about 68% of the area of ​​the outdoor heat exchanger in the existing system. The modification method as described in this paragraph is sometimes referred to as modification method 7D for convenience.

[0313] The present invention includes a method for retrofitting an existing split-type direct expansion vapor compression air conditioning system, which includes: (i) inter-unit refrigerant piping between an indoor unit and an outdoor unit; (ii) a reversing valve that allows the system to operate in a heating mode; (iii) existing high GWP refrigerants in the indoor unit and the outdoor unit, including R410A or R-22; (iv) an existing compressor; (v) an expansion valve in the outdoor unit, and (vi) an existing outdoor heat exchanger. According to the modification method of the present invention, the existing system is modified without replacing the main part of the inter-unit piping to produce a secondary loop system in which: (i) the refrigerant in the secondary loop is the refrigerant of the present invention, including each of refrigerants 1 to 5; (ii) the displacement of the compressor in the outdoor unit is about 4% to about 96% of the displacement of the compressor in the existing system; (iii) the heat transfer surface of the outdoor heat exchanger is about 16% to about 68% of the area of ​​the outdoor heat exchanger in the existing system; (iv) a replacement expansion valve is introduced into the system to work in the outdoor loop; (v) the saturation temperature drop in the suction line is 2°F or less; and (vi) the saturation temperature drop in the liquid line is 1°F or less. The modification method as described in this paragraph is sometimes referred to as modification method 7E for convenience.

[0314] use

[0315] The present invention includes using the refrigerants of the present invention (including each of Refrigerants 1 to 5) to provide heating and / or cooling to a fluid or object. The uses as described in this paragraph are sometimes referred to as heat transfer uses 1 for convenience.

[0316] The present invention also includes the use of the refrigerants of the present invention (including each of Refrigerants 1 to 5) in a secondary circuit air conditioning system, in the indoor circuit of such a system, to provide heating and / or cooling, and provides the unique advantages associated with such use. The use as described in this paragraph is sometimes referred to as heat transfer use 2 for convenience.

[0317] The present invention also includes the use of the refrigerant of the present invention (including each of Refrigerants 1 to 5) in a secondary circuit residential air conditioning system including the refrigerant of the present invention (including each of Refrigerants 1 to 5), in the indoor circuit of such a system to provide heating and / or cooling, and provides the unique advantages associated with such use. The use as described in this paragraph is sometimes referred to as heat transfer use 3 for convenience.

[0318] The present invention includes the use of the refrigerant of the present invention (including each of Refrigerants 1 to 5) to retrofit an existing single refrigerant vapor compression heat pump using an existing refrigerant (including R410A or R-22) to produce a pumped secondary loop system, wherein the refrigerant in the pumped secondary loop is the refrigerant of the present invention, including each of Refrigerants 1 to 5. The use as described in this paragraph is sometimes referred to as retrofit use 1 for convenience.

[0319] The present invention includes the use of the refrigerant of the present invention (including each of refrigerants 1 to 5) to retrofit an existing single refrigerant vapor compression heat pump air conditioning system using an existing refrigerant (including R410A or R-22) to produce a pumped secondary loop system, wherein the refrigerant in the pumped secondary loop is the refrigerant of the present invention, including each of refrigerants 1 to 5. The use as described in this paragraph is sometimes referred to as retrofit use 2 for convenience.

[0320] The present invention includes the use of the refrigerant of the present invention (including each of Refrigerants 1 to 5) to retrofit an existing single-refrigerant residential vapor compression heat pump air conditioning system using an existing refrigerant (including R410A or R-22) to produce a pumped secondary loop system, wherein the refrigerant in the pumped secondary loop is the refrigerant of the present invention, including each of Refrigerants 1 to 5. The use as described in this paragraph is sometimes referred to as retrofit use 3 for convenience.

[0321] Exemplary heat transfer systems, methods, and uses

[0322] As described in detail below, preferred methods, uses and systems of the present invention include or use a secondary loop air conditioning arrangement. In such an arrangement, the outdoor loop includes a compressor, a condenser, an expansion device and an evaporator, all of which are connected in a fluid communication manner using pipes, valves and a control system so that the outdoor refrigerant and the relevant components of the heat transfer composition can flow through the system in a known manner to complete a vapor compression refrigeration cycle. The indoor loop includes a pumped liquid refrigerant system, which includes a liquid refrigerant of the present invention (including each of Refrigerants 1 to 5), a pump for moving the liquid refrigerant in the loop, and a heat exchanger for exchanging heat between the indoor refrigerant and the indoor air.

[0323] Figure 1A and Figure 1B Schematic diagrams of the heat transfer system of the present invention are shown, the former showing operation in cooling mode and the latter showing operation in heating mode. Figure 1ADescribing the operating conditions in the cooling mode, the figure shows that the compressor 14 provides compressed outdoor refrigerant vapor to the outdoor heat exchanger 11 through the reversing valve 10 and the pipeline 8, and the outdoor heat exchanger acts as a condenser in the cooling mode for rejecting heat to the outdoor ambient air. The compressed refrigerant vapor condenses in the heat exchanger 11 to produce outdoor liquid refrigerant, which is directed to the expansion device, such as the expansion valve 12 via the pipeline 9, and the expansion device produces outdoor liquid refrigerant at a reduced temperature and pressure. The outdoor liquid refrigerant is then transported to the inter-circuit heat exchanger 13 through the pipeline 5. In a preferred embodiment, the expansion valve 12 is a replacement expansion valve, that is, the expansion valve has no function during the operation of the existing system, which is achieved by fixing the existing valve in an open position, bypassing the existing valve, or removing the existing valve. In this regard, particular reference is made to Figure 2A and Figure 2b, noting that in a typical existing R410A system, the expansion valve is upstream of the indoor evaporator coil and is physically located near the indoor coil / evaporator in the room. Since the preferred modification method of the present invention includes creating an indoor circuit as a pumped circuit, the indoor expansion valve will generally not be present. On the other hand, the outdoor circuit of the modification method according to the present invention will be a vapor compression circuit, in which case an expansion valve is required. Therefore, according to the modification method of the present invention, installing a replacement expansion valve located outdoors is a preferred step. In addition, those skilled in the art will recognize from the teachings contained herein that since the outdoor refrigerant formed by the present invention will not be R410A, the specific design features of the replacement expansion valve in such cases are preferably selected to achieve the desired operating conditions in the outdoor circuit in which the replacement refrigerant is used according to the present invention.

[0324] See again Figure 1A and Figure 1B , although the inter-circuit heat exchanger 13 is Figure 1A and Figure 1B 1 is shown as being located outside the residence in a preferred location, but it should be understood that in other embodiments, the inter-circuit heat exchanger can be located inside the residence. In the cooling mode, the inter-circuit heat exchanger 13 acts as an evaporator for the outdoor refrigerant, in which case the inter-circuit heat exchanger is preferably provided via a heat exchanger including Figure 1A The pumped secondary circuit of at least a portion of the lines 1 to 4 shown absorbs heat from the secondary (indoor) refrigerant of the present invention, including refrigerants 1 to 10. The outdoor refrigerant thus absorbs heat from the indoor refrigerant in the intermediate heat exchanger 13 to produce outdoor refrigerant vapor, which is delivered to the reversing valve 10 through the line 6 and then to the suction line 7 of the compressor 14.

[0325] The indoor refrigerant of the present invention (including refrigerants 1 to 10) circulates through a pumped secondary circuit including a receiver 15, a pump 16 and an indoor heat exchanger 17. In the cooling mode, the indoor heat exchanger 17 acts as an evaporator, which produces indoor refrigerant vapor via line 2, which is in turn delivered to the inter-circuit heat exchanger 13 via line 3. In the inter-circuit heat exchanger 13 in the cooling mode, the indoor refrigerant vapor condenses to produce indoor refrigerant liquid, which reaches line 4 and is then directed to the receiver 15. The receiver 15 directs the indoor refrigerant liquid to the pump 16, which provides energy to circulate the refrigerant through the circuit, in particular, through line 1 to the indoor heat exchanger. Preferably, the indoor circuit includes a flow valve (preferably a control valve 1A operated by an appropriate control circuit (not shown)), which is opened in the cooling mode to allow the indoor refrigerant to flow from the pump 16 to the evaporator 17. On the other hand, valves 1B and 1C located in lines 20 and 21 respectively (preferably also control valves operated by appropriate control circuits (not shown)) are closed during operation in cooling mode, but open in heating mode, as disclosed in detail below.

[0326] Now refer to the combination Figure 1B Describing the operation in the heating mode, the compressor 14 provides compressed outdoor refrigerant vapor through the reversing valve 10 and the pipeline 5 to the inter-circuit heat exchanger 13, which acts as a condenser in the heating mode, for preferably via Figure 1B The pumped secondary circuit shown rejects heat to the secondary (indoor) refrigerant of the present invention (including refrigerants 1 to 10). The outdoor liquid refrigerant condensed in the inter-circuit heat exchanger 13 is conveyed via line 6 to an expansion device (such as expansion valve 12), which produces outdoor liquid refrigerant at a reduced temperature and pressure, which is then conveyed to the outdoor heat exchanger 11 via line 7. In a preferred embodiment, the expansion valve 12 is a replacement expansion valve, that is, the expansion valve has no function during the operation of the existing system, which is achieved by fixing the existing valve in an open position, bypassing the existing valve, or removing the existing valve. In the outdoor heat exchanger 11, the outdoor liquid refrigerant absorbs heat from the outdoor ambient air to produce outdoor refrigerant vapor, which is then directed to the reversing valve 10 via line 8, which then directs the vapor flow to the inlet of the compressor 14 via line 9. The compressed outdoor refrigerant vapor is transferred to the inter-circuit heat exchanger 13, which acts as a condenser in the heating mode for rejecting heat to the secondary refrigerant, through the reversing valve 10 and the pipeline 5. The compressed refrigerant vapor is condensed in the inter-circuit heat exchanger 13 to produce outdoor liquid refrigerant by rejecting heat to the indoor refrigerant in the indoor circuit, as described in detail below.

[0327] In the heating mode, the indoor refrigerant of the present invention (including refrigerants 1 to 5) circulates through the same pumped secondary circuit used in the cooling mode, namely, the receiver 15, the pump 16 and the indoor heat exchanger 17, except that the flow path is as follows: Figure 1B Improvements have been made as shown and described herein. In the heating mode, the pumped circuit operates with valve 1A in the closed position and valves 1B and 1C open. In this configuration, the indoor liquid refrigerant flow is directed from the receiver 15 to the pump 16, but is directed to the line 3 leading to the inter-circuit heat exchanger 13 via the pipeline 21 and the valve 1C, where heat is absorbed from the outdoor refrigerant. Therefore, in the heating mode, the inter-circuit heat exchanger acts as an evaporator for the indoor refrigerant (including each of the refrigerants 1 to 5) of the present invention, producing indoor refrigerant vapor. The indoor refrigerant vapor is transported from the inter-circuit heat exchanger 13 to the indoor heat exchanger 17 via the pipeline 4, where the heat is discharged to the indoor air, thereby heating the residence. Therefore, in the heating mode, the indoor coil acts as a condenser for the indoor refrigerant of the present invention. The condensed liquid from the indoor heat exchanger 17 is then directed to the receiver 15 via the pipeline 2 and the valve 1B.

[0328] Example

[0329] In the following examples, refrigerant compositions according to the present invention are identified as compositions L1 to L4 in Table E below, and according to heat transfer systems and heat transfer methods, compositions L5 (which is R466A) are also used. Applicants have tested and evaluated each of L1 to L5 refrigerants, and found that they are non-flammable, that is, A1 class refrigerants, and have also performed thermodynamic analysis on each of L1 to L5 to determine its ability to match R-410A performance when used in a single refrigerant vapor compression heat pump air conditioning system. For the characteristics of each binary and ternary component pair used in refrigerant, the collected experimental data are used for analysis. In the experimental evaluation, each pair of composition changes in a series of relative percentages, and each pair of mixture parameters is regressed into experimentally obtained data. The known vapor / liquid equilibrium behavior data derived from the U.S. Institute of Science and Technology (NIST) reference fluid thermodynamics and transport properties database software (Refprop 9.1NIST standard database 23, from April 2016) are used for embodiments. Each blend was also evaluated to determine its flammability classification as described above.

[0330] Table E: Test performance of the refrigerant of the present invention

[0331]

[0332] As can be seen from the above Table E, each of the refrigerants L1 to L4 according to the present invention achieves a GWP value (AR4) of 750 or less while achieving Class A1 flammability. This is also the case with R466A.

[0333] Comparative Example 1 – Single Refrigerant Residential Heat Pump Using R410A – Cooling Mode

[0334] Use R410A as a single refrigerant and usually corresponds to Figure 2A The residential heat pump air conditioning system of the basic structure shown is called a ductless mini-split system and operates in cooling mode (such as Figure 2A ). The system includes a compressor, an outdoor condenser, an expansion valve, an indoor evaporator, and a reversing valve. Typically when this type of system is operating in a cooling mode, the reversing valve is set to direct the high temperature vapor from the compressor to the inlet of the outdoor condenser, where the vapor rejects heat to the outdoor ambient air. The liquid refrigerant leaving the condenser is then directed to the expansion valve, which reduces the pressure and produces a lower pressure refrigerant liquid whose temperature is lower than the temperature of the ambient air set point inside the residence. The cold liquid refrigerant leaving the expansion device is directed to the indoor evaporator. In the evaporator, as the cold refrigerant evaporates, heat is absorbed by the refrigerant, thereby cooling the indoor air in the residence. The vapor flow from the evaporator is directed to the reversing valve, which is set to direct the refrigerant vapor flow back to the suction side of the compressor. In a typical arrangement, the compressor and condenser are both located outside the residence, while the evaporator is located inside the residence. The basic system operating conditions of this comparative example are:

[0335] 1. Refrigerant condensation temperature = 45°C, corresponding outdoor ambient temperature = 35°C

[0336] 2. Expansion device subcooling = 5.0℃

[0337] 3. Refrigerant evaporation temperature = 10°C, corresponding indoor room temperature = 27°C

[0338] 4. Evaporator overheat = 5.0℃

[0339] 5. Volumetric efficiency = 100%

[0340] 6. Isentropic efficiency = 74%

[0341] For purposes of relative comparison, performance results in terms of capacity and efficiency are considered 100%, compressor displacement and heat transfer surface area of ​​the heat exchanger are considered 100%, and compressor horsepower is considered 100%.

[0342] Example 1A - Using various low GWP refrigerants in the outdoor circuit and refrigerants L1 to L5 in the indoor circuit And increase the compressor displacement to match the capacity of the secondary circuit residential heat pump

[0343] Usually corresponds to Figure 1AThe micro-secondary residential air conditioning system of the present invention of the basic structure shown is operated in a cooling mode as described herein. The system was tested using 15 different refrigerant pairs, namely, each of three different outdoor refrigerants (propane, R454B and R32) was paired with four indoor refrigerants of the present invention (i.e., L1, L2, L3 and L4) and L5, each as identified in Table E above. The system is configured to use substantially the same equipment as used in Comparative Example 1 in the outdoor loop, except that the compressor size is increased by a sufficient amount to provide 100% capacity relative to Comparative Example 1, as identified in Table E1A below, and the expansion valve is a replacement expansion valve as described herein. The operating conditions are as follows:

[0344] 1. Condensation temperature = 45°C, corresponding outdoor ambient temperature = 35°C

[0345] 2. Expansion device subcooling = 5.0℃

[0346] 3. Evaporation temperature = 5.0°C, corresponding indoor room temperature = 27°C

[0347] 4. Evaporator overheat = 0.0℃ (flooding)

[0348] 5. Intermediate heat exchanger superheat = 5.0℃

[0349] 6. Volumetric efficiency = 100%

[0350] 7. Saturation temperature difference of heat exchanger between circuits = 5°C

[0351] Therefore, the same operating conditions as used in Comparative Example 1 were used, except that the evaporation temperature of the refrigerant in the pumped indoor circuit was 5°C lower than the temperature used in Comparative Example 1. The results are recorded in Table E1 below relative to the results of the Comparative Example:

[0352] Table E1A

[0353]

[0354]

[0355] Example 1B - Using various low GWP refrigerants in the outdoor loop and refrigerants L1 to L4 in the indoor loop Secondary circuit residential heat pump with increased condenser heat transfer surface to improve efficiency

[0356] The micro-secondary residential air conditioning system of the present invention as described in Example 1A was operated in a cooling mode as described in Example 1A, except that: (1) the heat transfer area of ​​the outdoor heat exchanger was increased relative to the condenser in Comparative Example 1, and the expansion valve was replaced as described in Example 1; and (2) the condenser temperature was reduced relative to Comparative Example 1. The system was tested using 15 different refrigerant pairs, namely, each of three different outdoor refrigerants (propane, R454B and R32) was paired with four indoor refrigerants of the present invention (i.e., L1, L2, L3 and L4) and L5, each as identified in Table E above. The results are recorded in Table E1B below relative to the results of Comparative Example 1:

[0357] Table E1B

[0358]

[0359]

[0360] As illustrated by the results in Example 1B, the secondary loop system of the present invention is capable of achieving efficiencies of at least about 93% in each case, and greater than 95% in the case of propane as the outdoor refrigerant. This is an unexpected and highly desirable result due to the significantly reduced GWP of the refrigerants used in the innovative system of the present invention.

[0361] Example 1C - Using various low GWP refrigerants in the outdoor loop and refrigerants L1 to L5 in the indoor loop And secondary circuit residential heat pump with high efficiency compressor

[0362] The micro-secondary residential air conditioning system of the present invention as described in Example 1B operates in the cooling mode as described in Example 1B, except that a compressor with the same displacement but higher efficiency is used. Specifically, the compressor used in this example has an efficiency that is about 2% higher than the compressor of Example 1B. The results are recorded in the following Table E1C relative to the results of Comparative Example 1:

[0363] Table E1C

[0364]

[0365]

[0366] Comparative Example 2 – Single Refrigerant Residential Heat Pump Using R410A – Heating Mode

[0367] Use R410A as a single refrigerant and usually corresponds to Figure 2B The basic structure of the residential heat pump air conditioning system, known as a ductless mini-split system, is shown in the heating mode (eg Figure 2BAs shown). The system includes a compressor, an outdoor condenser, an expansion valve, an indoor evaporator and a reversing valve. Typically when this type of system is operated in a heating mode, the reversing valve is set to direct high temperature vapor from the compressor to the inlet of the indoor condenser, where the hot vapor heats the indoor ambient air when it condenses in the refrigerant liquid. The liquid refrigerant leaving the condenser is then directed to the expansion valve, which reduces the pressure and produces a lower pressure refrigerant liquid that is lower in temperature than the outdoor ambient air. The cold liquid refrigerant leaving the expansion device is directed to the outdoor evaporator, where in the heating mode, the cold liquid refrigerant absorbs heat to produce refrigerant vapor, which is directed by the reversing valve to the suction side of the compressor. In a typical arrangement, the compressor and evaporator are both located outside the residence, while the condenser is located inside the residence. The basic system operating conditions of this comparative example are:

[0368] 1. Evaporation temperature = 0.5°C, corresponding outdoor ambient temperature = 8.3°C

[0369] 2. Evaporator overheat = 5.0℃

[0370] 3. Condensation temperature = 40.0℃, corresponding indoor room temperature = 21.1℃

[0371] 4. Expansion device subcooling = 5.0℃

[0372] 5. Volumetric efficiency = 100%

[0373] For the purpose of relative comparison, the performance results in terms of capacity and efficiency are considered to be 100%, the compressor displacement and the heat transfer surface area of ​​the heat exchanger are considered to be 100%.

[0374] Example 2A - Using various low GWP refrigerants in the outdoor circuit and refrigerants L1 to L5 in the indoor circuit Secondary circuit residential heat pump with increased compressor displacement to match capacity – Heating mode

[0375] Usually corresponds to Figure 1B The micro secondary residential air conditioning system of the present invention is shown in the basic structure Figure 1A The system is the same as that of Comparative Example 2, but operated in heating mode as described herein. The system was tested using 9 different refrigerant pairs, namely, each of three different outdoor refrigerants (propane, R454B, and R32) was paired with five indoor refrigerants of the present invention (i.e., L1, L2, L3, L4, and L4), each as identified in Table E above. The system was configured to use substantially the same equipment as used in Comparative Example 2 in the outdoor loop, except that the compressor size was increased by a sufficient amount to provide 100% capacity relative to Comparative Example 2, as identified in Table E2A below, and the expansion valve was a replacement valve as described herein. The operating conditions are as follows:

[0376] 1. Evaporation temperature = 0.5°C, corresponding outdoor ambient temperature = 8.3°C

[0377] 2. Ambient temperature – evaporation temperature = 7.8°C

[0378] 3. Evaporator overheat = 5.0℃

[0379] 4. Evaporation temperature = 5.0°C, corresponding indoor room temperature = 27°C

[0380] 5. Condensation temperature = 45.0°C, corresponding indoor room temperature = 21.1°C

[0381] 6. Expansion device subcooling = 5.0℃

[0382] 7. Volumetric efficiency = 100%

[0383] 8. Saturation temperature difference of intermediate heat exchanger = 5°C

[0384] Therefore, the same operating conditions as used in Comparative Example 2 were used, except that the condensing temperature of the refrigerant in the pumped indoor circuit was 45°C, 5°C higher than the condensing temperature used in Comparative Example 2. The results are recorded in Table E2A below relative to the results of Comparative Example 2:

[0385] Table E2A

[0386]

[0387]

[0388] Example 2B - Using various low GWP refrigerants in the outdoor circuit and refrigerants L1 to L5 in the indoor circuit Secondary circuit residential heat pump with increased evaporator heat transfer surface for improved efficiency – Heating mode

[0389] The micro-secondary residential air conditioning system of the present invention as described in Example 1A was operated in a heating mode as described in Example 2A, except that: (1) the heat transfer area of ​​the outdoor heat exchanger was increased relative to the evaporator in Comparative Example 2, and (2) the evaporator temperature was reduced relative to Example 2A. The system was tested using 9 different refrigerant pairs, namely, each of three different outdoor refrigerants (propane, R454B, and R32) was paired with five indoor refrigerants of the present invention (i.e., L1, L2, L3, L4, and L5), each as identified in Table E above. The results are recorded in Table E2B below relative to the results of Comparative Example 2:

[0390] Table E2B

[0391]

[0392]

[0393] As illustrated by the results in Example 2B, the secondary loop system of the present invention is capable of achieving efficiencies of at least about 89% in each case, and greater than 93% in the case of propane as the outdoor refrigerant. This is an unexpected and highly desirable result due to the significantly lower GWP of the refrigerants used in the innovative system of the present invention, and due to the superior performance achieved when the same system is operated in a cooling mode.

[0394] Example 2C - Using various low GWP refrigerants in the outdoor loop and refrigerants L1 to L5 in the indoor loop And secondary circuit residential heat pump with high efficiency compressor – heating mode

[0395] The micro-secondary residential air conditioning system of the present invention as described in Example 1B operates in the cooling mode as described in Example 1B, except that a compressor with the same displacement but higher efficiency is used. Specifically, the compressor used in this example has an efficiency that is about 2% to 5% higher than the compressor of Example 2B. The results are recorded in the following Table E2C relative to the results of Comparative Example 2:

[0396] Table E2C

[0397]

[0398]

[0399] Example 3 - Using various low GWP refrigerants in the outdoor circuit and refrigerant L1 in the indoor circuit Secondary circuit residential heat pump to L5 retrofits existing single refrigerant R-410A heat pump

[0400] Provides the use of R410A and has Figure 2A and Figure 2B An existing residential air conditioning / heat pump system of the configuration shown in FIG. In the existing system, the following components are located in the outdoor unit: compressor, reversing valve, outdoor heat exchanger (condenser), and expansion valve. Refrigerant flow lines flowing into and out of the outdoor unit circulate the refrigerant to the indoor unit containing the indoor heat exchanger. The existing system has a capacity of 10.5 KW and has the following nominal operating parameters:

[0401] 1. Evaporation temperature = 10°C, corresponding indoor ambient temperature = 27°C

[0402] 2. Evaporator overheat = 5°C

[0403] 3. Condensation temperature = 45°C, corresponding outdoor room temperature = 35°C

[0404] 4. Expansion device subcooling = 5.0℃

[0405] 5. Compressor isentropic efficiency = 74%

[0406] 6. Volumetric efficiency = 100%

[0407] 7. Enthalpy change = 164 kJ / kg

[0408] 8.Mass flow rate = 0.064kg / s

[0409] 9. Volume flow rate = 0.0016m 3 / s

[0410] The system was modified by removing substantially all of the R-410A refrigerant from the system using standard industry techniques. The system was modified to have a 100% RH system by disconnecting the refrigerant flow lines at or near the outdoor unit, but without replacing those refrigerant flow lines to and from the indoor unit. Figure 1A and Figure 1B The configuration shown. An intermediate heat exchanger, receiver, and liquid pump as disclosed herein are added to the system so that they are located in the indoor unit. Existing refrigerant flow lines leading to and from the indoor unit are used to allow refrigerant to flow to and from the pump and to and from the inter-circuit heat exchanger, and these existing refrigerant flow lines are used to transport indoor refrigerant between the pump and the indoor heat exchanger and between the inter-circuit heat exchanger and the indoor heat exchanger. As noted in Examples 1A and 1B, the outdoor compressor displacement is increased and the outdoor heat exchanger surface area is increased, such as Figure 1A and Figure 1B Additional indoor refrigerant flow lines and valves are added as shown to allow operation in heating mode. The expansion valve is replaced as described herein. Based on a system capacity of 10.5KW, an evaporating temperature of 10°C, an inlet mass of 0 and an outlet mass of 0.86, the modified system operates with a certain mass flow rate of indoor refrigerants L1 to L5. For each of the refrigerants L1 to L4 of the present invention, as well as refrigerant L5, the performance of the modified system in terms of Δ enthalpy and the mass flow rate and volume flow rate of indoor refrigerant through the existing pipeline is recorded in the following Table E3, where the operating conditions in the original R-410A system are included in Table E3A for comparison:

[0411] Table E3A

[0412]

[0413] Based on the operating conditions as recorded in Table E3A, the operating conditions of the existing refrigerant flow lines between the outdoor unit and the indoor unit in the retrofitted system are determined and recorded in Table E3B below:

[0414] Table E3B

[0415]

[0416]

[0417] As will be appreciated by those skilled in the art, the retrofitted system of the present invention using existing refrigerant flow lines provides acceptable performance in terms of indoor refrigerant pressure drop in the existing connecting lines. Based on industry standards, the maximum saturation temperature drop in the suction line is considered to be 2°F (1.1°C) and the maximum saturation temperature drop in the liquid line is 1°F (0.56°C). As recorded in Table E3B above, these standards are met due to the retrofit method of the present invention.

Claims

1. A refrigerant comprising at least about 95 weight percent of the following four components based on all refrigerant components: (a) from about 50.5 weight percent to about 52.5 weight percent HFO-1234yf, (b) about 35.5 to 41 weight percent HFC-134a; (c) 2.2 wt% to 5.5 wt% HFC-125; and (d) 3.8 to about 8 weight percent HFC-32, wherein the percentages are based on the total amount of (a) to (d).

2. The refrigerant according to claim 1, consisting essentially of: from about 50.5 wt % to about 52.5 wt % HFO-1234yf, about 35.5 wt % to 41 wt % HFC-134a; 2.2 wt% to 5.5 wt% HFC-125; and 3.8 wt % to about 8 wt % HFC-32.

3. The refrigerant of claim 1, consisting essentially of: 51 to 52.5 wt. % of HFO-1234yf, 35.8 to 37.8 wt. % HFC-134a; 4.5 to 5.5 wt. % HFC-125; and 6 to 8 wt% HFC-32.

4. A secondary circuit residential refrigeration system comprising an indoor refrigerant according to claim 1 and an outdoor refrigerant comprising propane, R454B or R32.

5. A method for retrofitting an existing residential heat pump air conditioning system, the existing residential heat pump air conditioning system using a vapor compression cycle with R410a as the refrigerant and a reversing valve to provide heating or cooling to indoor air in a residence, the method comprising: (a) providing an existing heat pump system, the heat pump system comprising: a.Compressor; b. an outdoor heat exchanger for exchanging heat between outdoor air and the R410A refrigerant; c. an indoor heat exchanger, the indoor heat exchanger being used to exchange heat between indoor air and the R410A refrigerant; d. a reversing valve connected to the inlet and outlet of the compressor, and each of the outdoor heat exchanger and the indoor heat exchanger; e. an expansion valve connected between the outdoor heat exchanger and the indoor heat exchanger; (b) disconnecting the indoor heat exchanger from the expansion valve and the reversing valve; (c) providing an inter-circuit heat exchanger, connecting the inter-circuit heat exchanger to the expansion valve and the reversing valve to provide a flow path for the R410A refrigerant to pass through the inter-circuit heat exchanger; (d) generating a secondary circuit including the indoor heat exchanger and the inter-circuit heat exchanger; and (e) providing an indoor refrigerant in the secondary loop, the indoor refrigerant comprising at least about 95 weight percent of the following components, based on all refrigerant components: a. about 50.5 wt % to about 52.5 wt % HFO-1234yf; b. about 35.5 wt % to 41 wt % HFC-134a; c. 2.2 wt% to 5.5 wt% HFC-125; and d. 3.8 wt % to about 8 wt % HFC-32, wherein the percentages are based on the total amount of a. to d.

6. The method of claim 5, wherein the step of creating the secondary circuit further comprises including a liquid pump connected between the indoor heat exchanger and the inter-circuit heat exchanger.

7. The method of claim 6, wherein the step of creating the secondary circuit further comprises including a liquid receiver upstream of the pump and including pipes and valves that can be alternatively connected to the indoor heat exchanger or the inter-circuit heat exchanger.

8. A method for modifying an existing split-type direct expansion vapor compression air conditioning system, the existing split-type direct expansion vapor compression air conditioning system having an indoor unit including an indoor heat exchanger, an outdoor unit including a compressor and an outdoor heat exchanger, a refrigerant flow line connected between the indoor unit and the outdoor unit, and R410A in the indoor unit and the outdoor unit, the method comprising: (a) disconnecting the refrigerant flow line at or near the outdoor unit; (b) removing the R410A refrigerant from the indoor unit and the outdoor unit; (c) forming an outdoor refrigeration circuit including the compressor, the outdoor heat exchanger, and a refrigerant having a GWP of less than 750; (d) forming an indoor circuit refrigeration system including the indoor heat exchanger and a refrigerant, wherein the refrigerant comprises at least about 95% by weight of the following components based on all refrigerant components: a. about 50.5 wt % to about 52.5 wt % HFO-1234yf, b. about 35.5 wt % to 41 wt % HFC-134a; c. 2.2 wt % to 5.5 wt % HFC-125; and d. 3.8 wt % to about 8 wt % HFC-32, wherein the percentages are based on the total amount of a. to d.; and (e) providing an inter-circuit heat exchanger thermally connecting the indoor circuit and the outdoor circuit.

9. The reconstruction method according to claim 8, wherein the indoor circuit is connected to the outdoor circuit using the existing refrigerant flow line.

10. The reconstruction method according to claim 9, wherein the inter-circuit heat exchanger is located in the outdoor unit, and wherein the outdoor circuit is connected to the inter-circuit heat exchanger using the existing refrigerant flow line.

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