MX2015002083A - Low gwp heat transfer compositions. - Google Patents

Abstract

Heat transfer compositions and methods including (a) HFC-32; (b) HFO-1234ze; and (c) either or both of HFC-152a and/or HFC-134a.

Description

COMPOSITIONS OF HEAT TRANSFER WITH LOW POTENTIAL OF GLOBAL WARMING Cross reference to related requests The present application claims priority to the provisional application of E.U.A. with serial number 61 / 684,883, filed on August 20, 2012, the content of which is incorporated herein by reference in its entirety.

This application is also a continuation in part of the application of E.U.A. with serial number 13 / 292,374, filed on November 9, 2011, which claims the priority benefit of the provisional application of E.U.A. with number 61 / 413,000, filed on November 12, 2010, the contents of each of which is incorporated herein by reference in its entirety.

Field of the invention This invention relates to compositions, methods and systems which have utility particularly in refrigeration applications, and in particular aspects to heat transfer compositions and refrigerants useful in systems which typically use the HCFC-22 refrigerant for heating and / or cooling applications. .

BACKGROUND OF THE INVENTION Mechanical refrigeration systems and related heat transfer devices, such as heat pumps and air conditioners, which use coolants are well known in the art for industrial, commercial and domestic uses. Chlorofluorocarbons (CFCs) were developed in the 1930s as refrigerants for such systems. However, since the 1980s, the effect of CFCs on the stratospheric ozone layer has become the focus of much attention. In 1987, several governments signed the Montreal Protocol to protect the global environment that sets a timetable for withdrawing CFC products. The CFCs were replaced by more environmentally acceptable materials containing hydrogen or hydrochlorofluorocarbons (HCFC). Further modifications to the Montreal Protocol accelerated the phase-out of these CFCs and also programmed the phase-out of HCFCs.

Accordingly, there has been an increasing need for new fluorocarbon and hydrofluorocarbon compounds and compositions that are attractive alternatives to the compositions previously used in these and other applications. For example, it has been desirable to modernize the refrigeration and air-conditioning systems containing chlorine by substituting the compositions of heat transfer containing chlorine by compounds that do not contain chlorine, which do not deplete the ozone layer, such as hydrofluorocarbons (HFC). The industry in general and the heat transfer industry, in particular, are continually looking for new mixtures based on fluorocarbons that offer alternatives to, and are considered environmentally safe substitutes for, CFCs and HCFCs. In general, it is considered important, however, at least with respect to heat transfer fluids, that any potential substitute must also possess those properties present in many of the most widely used fluids, such as excellent heat transfer properties. , chemical stability, low or no toxicity, low flammability and / or lubricant compatibility, among others. R-22 provides an example of a refrigerant composition of this type that is used in many refrigeration and air-conditioning systems, which is being eliminated by previous environmental concerns.

A number of patent publications have suggested substitutes for HCFC-22. That is, these patent publications have suggested refrigerant or air-conditioning compositions, that is, they can be used in place of HCFC-22 in new systems that are built or installed. Among said patent publications is included the patent of E.U.A. No. 5,185,094, patent of US Pat. No. 5,370,811, patent of US Pat. No. 5,438,849, patent of US Pat. No. 5,643,492, patent of E.U.A. 5,709,092, patent of E.U.A. 5,722,256, patent of E.U.A. 6,018,952, patent of E.U.A. 6,187,219 Bl, patent of E.U.A. 6,606,868 Bl, patent of E.U.A. 6,669,862 Bl, the application of E.U.A. published No. US 2004/00691091 Al, and published European applications Nos. EP 0 430169 Al, EP 0 509 673 Al and EP 0 811 670 Al. Although many of these patents of E.U.A. and published applications describe ternary mixtures of difluoromethane (HFC-32), pentafluoroethane (HFC-125) and tetrafluoroethane (HFC 134a) for use in refrigeration or air-conditioning systems, none of which faces the capacity to replace HCFC-22 to obtain a significant reduction of GWP and at the same time a similar performance of R-22 without the need to modify the system, especially without the need to replace the main components (for example, the compressor and the expansion valve). In order to replace the R-22 in current R-22 AC systems, for example, it is necessary that the operating characteristics of the replacement refrigerant, such as evaporator superheat, cooling capacity, mass flow rate of the Refrigerant, efficiency and pressures are very close to those of the HCFC-22 refrigerant that is being replaced by the particular heat transfer and other specifications for the existing system. This close coincidence in the properties of the replacement refrigerant with those of HCFC-22 in the original system is essential for use in such existing AC systems or systems designed for the use of R-22 refrigerant, to avoid replacement or modification of equipment, for example, replacement or modification of expansion valves.

In terms of efficiency, then, it is also important to bear in mind that a loss in energy efficiency or thermodynamic efficiency of the refrigerant can have secondary environmental impacts through a greater use of fossil fuels derived from a greater demand for electrical energy. Therefore, it is desirable that the substitution have an equivalent or almost equivalent efficiency to R-22.

Furthermore, it is generally considered desirable that substitutes of CFC and / or HFC refrigerants be effective without major engineering changes to the conventional vapor compression technology currently used with CFC and / or HFC refrigerants.

Flammability is another important property for many applications. That is, it is considered important or essential in many applications, including particularly in heat transfer applications, to use compositions that are not flammable or have mild flammability. Therefore, it is often beneficial that in said Compositions are used that are slightly flammable, or even that are less flammable than slightly flammable. As used herein, the term "slightly flammable" refers to compounds or compositions that are classified as 2L in accordance with the ASHRAE Standard 34 dated 2010, which is incorporated herein by reference. Unfortunately, many of the HFCs that might otherwise be desirable for use in refrigerant compositions are flammable and classified as 2 and 3 by ASHRAE. For example, fluoroalkane difluoroethane (HFC-152a) has flammability A2 and is therefore not viable to be used in pure form in many applications.

Applicants have therefore come to appreciate the need for compositions, and particularly heat transfer compositions, which are highly advantageous in vapor compression and heating and cooling methods and, in particular, systems designed for use with R-22. .

Summary of the invention Applicants have found that the need indicated above, and other needs, can be met in accordance with one aspect of the invention by the compositions, methods, uses and systems comprising or using a multi-component mixture comprising: (a) HFC-32; (b) more than 25% HFO-1234ze, and (c) optionally, but in certain embodiments, preferably HFC-152a and / or HFC-134a. In preferred but not limiting aspects of the present invention, the amounts of each of the components (a), (b) and (c) are selected to ensure that the combustion rate of the composition is less than about 10, the global warming potential of the composition is less than about 500, and the capacity in AC, refrigerant or heat pump systems is within about 10%, or in other embodiments within about 8%, of the capacity of the R- 22, in particular, but not exclusively, when tested under heating and / or cooling test conditions identified herein. With respect to the latter, in certain embodiments, the composition has a capacity greater than 95% of R-22 and less than 115% of R-22; in certain modalities, the capacity is greater than 95% of R-22 and less than 110% of R-22; and in other modalities, the capacity is greater than 95% and less than 108% of R-22.

In certain aspects of the foregoing or any embodiment herein, component (b) may further comprise at least one compound selected from unsaturated propenes terminated in -CF3, unsaturated butenes terminated in -CF3, and combinations thereof, wherein he compound is a compound other than HFO-1234ze.

In other embodiments, the compositions of the present invention may include (a) from about 33% to about 55% by weight of HFC-32; and (b) from about 25% to about 66% by weight of HFO-1234ze; and (c) more than about 0% to about 30% by weight of HFC-152a, HFC-134a, or combinations thereof. In other embodiments, the compositions include (a) from about 35% to about 55% by weight of HFC-32; (b) from about 30% to about 55% by weight of HFO-1234ze and (c) from more than about 0% to about 22% by weight of HFC-152a or more from about 0% to about 15% by weight of HFC-134a. Unless otherwise indicated herein, the term "% by weight" refers to the weight percent based on the total of components (a) - (c) in the composition.

In other preferred embodiments, the compositions of the present invention include (a) from about 33% to about 55% by weight of HFC-32; (b) more than 25% of HFO-1234ze, (c) more than about 0% to about 25% by weight of HFC-152a; and (d) greater than about 0% to about 20% by weight of HFC-134a, wherein in certain aspects, the total amount of HFC-152a and HFC-134a does not exceed 30% by weight. In other embodiments, the compositions include (a) from about 35% to about 55% by weight of HFC-32; (B) from about 30% to about 55% by weight of HFO-1234ze; (c) more than about 0% to about 22% by weight of HFC-152a; and (d) more than about 0% to about 15% by weight of HFC-134a, wherein in certain aspects, the total amount of HFC-152a and HFC-134a does not exceed 30% by weight. Unless otherwise indicated herein, the term "% by weight" refers to percent by weight based on the total of components (a) - (d) in the composition.

Again, in certain preferred aspects, the heat transfer compositions, methods, uses and systems of the present invention provide a composition with a GWP (as defined below) of not more than 500, and most preferably not yet greater than about 400, and most preferably still not more than about 350. The compositions, methods, uses, and heat transfer systems of the present invention also preferably provide said composition with the level of ignition risk (as defined below) of not more than about 7, even very preferably not greater than about 5. It is also generally preferred that the compositions of the present invention have a burn rate (as defined below) of no more than about 10. The compositions, methods, uses and Heat transfer systems of the present invention also preferably provide a capacity, in particular in AC, refrigerant and heat pump systems, which is within about 10%, or in other embodiments within about 8%, of the capacity of the R-22. In other embodiments, the composition has a capacity greater than 95% of R-22 and less than 115% of R-22, greater than 95% of R-22 and less than 110% of R-22, or greater than 95% and less than 108% of R-22.

In certain preferred embodiments, component (b) of the present invention comprises, consists essentially of, or consists of HFO-1234ze. The term HFO-1234ze is used herein generically to refer to 1. 1.1.3-tetrafluoropropene, regardless of whether it is of the cis or trans form. The terms "cisHFO-1234ze" and "transHFO-1234ze" are used here to describe the cis and trans forms of 1. 1.1.3-tetrafluoropropene respectively. The term "HFO-1234ze" therefore includes within its scope cisHFO-1234ze, transHFO-1234ze, and all combinations and mixtures thereof.

Brief description of the figures Figure 1 illustrates the combustion rate (BV) of a mixture of HFC-152a and 1234ze (E).

Figure 2 illustrates the combustion speed (BV) of a mixture of HFC-32 and 1234ze (E).

Figure 3 illustrates a schematic of the experimental configuration for flammable gas testing.

Detailed description of the preferred modalities R-22 is commonly used in low temperature refrigeration systems and certain air conditioning systems. It has an estimated Global Warming Potential (GWP) of 1810, which is much higher than what is desired or required. Applicants have found that the compositions of the present invention exceptionally and unexpectedly satisfy the need for new compositions for such applications, particularly, but not exclusively, air conditioning systems, heat pump systems, and commercial refrigeration, having better performance with respect to environmental impact while at the same time providing other important performance characteristics, such as capacity, efficiency, flammability and toxicity. In preferred embodiments, the present compositions provide alternatives and / or replacements for the refrigerants currently used in said applications, particularly and preferably HCFC-22, which at the same time have lower GWP values and provide a refrigerant composition having a degree of flammability that is slightly flammable or even less flammable than slightly flammable, and having desirably low toxicity, and preferably also have a close coincidence in the cooling capacity with HCFC-22 in such systems.

In certain aspects of the present application, the compositions have a capacity of AC, refrigerant or heat pump systems within about 10%, or in other embodiments within about 8%, of the heating or cooling capacity of R-22. , when tested under heating and cooling test conditions. The term "air conditioning system" or "AC system" refers to any system that cools or heats the air in a given environment. An example of test conditions that can be used to assess the capacity in such systems is provided in Example 3, below, which measures the capacity of a given composition having the start air temperature, start condenser temperature, temperature of the start evaporator, and the like. An expert in the art, however, will readily appreciate that the present invention is in no way limited to the conditions and parameters of initiation provided and that the test conditions may be varied in accordance with industry standard practice or other as known in the art. Non-limiting intervals for a condenser temperature, for example, can be 35 ° C to 55 ° C for heating and cooling, and non-limiting intervals, for an evaporator temperature can be 3 ° C to 14 ° C for a heating application and -20 ° C to 14 ° C for an application of cooling. An expert in the art will appreciate that said variation in the test procedures is intended to simulate the variation of the different environments and the required change of the ambient temperature in a given space.

As mentioned above, the present invention achieves outstanding advantages in relation to commercial refrigeration systems and, in certain preferred aspects, stationary refrigeration systems. Non-limiting examples of such stationary cooling systems are provided in Examples 4 and 5, below. For such purpose, said systems can include commercial applications of low temperature (Example 6), including commercial freezers or systems that can be used for storage and maintenance of frozen products. They may also include the commercial application of medium temperatures (example 5), such as commercial refrigerators, including systems for the storage of fresh products. The following examples provide typical conditions and parameters that are used for those applications. These conditions, however, are not considered as limiting the invention, since an expert in The technician will appreciate that they can be varied based on one or more of a myriad of factors, including but not limited to, environmental conditions, intended application, time of year, and the like. Said examples are also not necessarily limiting to the definition of the terms "stationary refrigeration" or "commercial refrigeration". The compositions provided herein may be used in similar type systems or, in certain embodiments, in any alternative system where R-22 is or may be adapted for use as a refrigerant.

It is contemplated that in certain embodiments, the present invention provides retrofitting methods comprising the replacement of at least a substantial portion of the heat transfer fluid (including the refrigerant and, optionally, the lubricant) in an existing system with a composition of the present invention, without substantial modification of the system. In certain preferred embodiments, the replacement step is a one-on-one replacement in the sense that a substantial redesign of the system is not required and no important element of the equipment needs to be replaced to accommodate the composition of the present invention as the fluid of heat transfer. In certain preferred embodiments, the methods comprise a one-for-one replacement in which the capacity of the system is at least about 70%, preferably at least about 85%, most preferably still at least about 90%, and most preferably still at least about 95% of the system capacity before replacement, and preferably not more than about 130%, most preferably even less of about 115%, most preferably still less than about 110%, and most preferably still less than about 105%. In certain preferred embodiments, the methods comprise a one-by-one replacement in which the suction pressure and / or discharge pressure of the system, and most preferably still both, is / are at least about 70%, most preferably at least about 90% and most preferably still at least about 95% of the suction pressure and / or the discharge pressure before replacement, and preferably not more than about 130%, most preferably still less than about 115, most preferably still less than about 110%, and most preferably still less than about 105%. In certain preferred embodiments, the methods comprise a one-by-one replacement in which the mass flow of the system is at least about 80%, most preferably at least 90%, and most preferably at least 95% of the mass flow before replacement, and preferably not more than about 130%, very preferably still less than about 115, most preferably still less than about 110%, and most preferably still less than about 105%.

Heat transfer compositions The compositions of the present invention are generally adaptable for use in heat transfer applications, i.e., as a heating and / or cooling medium, but are particularly well suited for use, as mentioned above, in AC systems. , heat pumps, and commercial refrigeration, or any other system that until now has used R-22.

Applicants have found that the use of the components of the present invention within the ranges indicated is important to achieve the important, but difficult to achieve combinations of properties presented by the present compositions, especially in the preferred systems and methods, and that the Use of these same components but substantially outside the identified ranges can have a detrimental effect on one or more of the important properties of the compositions of the invention.

In certain preferred embodiments, HFC-32 is present in the compositions of the invention in an amount from about 33% to about 55% by weight of the compositions.

In certain preferred embodiments, the second component comprises, consists essentially of, consists of HFO-1234ze, which may be included in an amount of about or greater than 25% by weight or from about 25% to about 66% by weight. In certain preferred aspects, HFO-1234ze, comprises, consists essentially of, or consists of trans-HFO-1234ze. This second component may also include one or more additional compounds, other than HFO-1234ze, which may be selected from unsaturated propenes terminated in -CF3, unsaturated butenes terminated in -CF3, and combinations thereof, but in other respects may include one or more additional compounds other than HFO-1234ze.

The compositions of the above may include (a) from about 40% to about 50% by weight of HFC-32; and (b) from about 50% to about 60% by weight of HFO-1234ze. Again, in certain embodiments, component (b) comprises, consists essentially of, or consists of HFO-1234ze.

In other preferred embodiments, the compositions of the present invention include HFC-152a in an amount of more than about 0% to about 25% by weight, or in certain embodiments of more than about 0% a about 22% by weight. In other embodiments, HFC-152a is provided in an amount of from about 1% to about 22% by weight, from about 3% to about 22% by weight, or from about 5% to about 22% by weight. Said compositions may also or alternatively include HFC-134a in an amount greater than about 0% to about 20% by weight, or in certain embodiments from greater than 0% to about 18% by weight. In certain aspects, the composition includes HFC-152a, HFC-134a, or combinations thereof in an amount of more than 0% by weight to about 30% by weight.

Other compositions of the foregoing may include (a) from about 33% to about 55% by weight of HFC-32; (b) from about 25% to about 66% by weight of HFO-1234ze; and (c) more than about 0% to about 25% by weight of HFC-152a or HFC-134a. In other embodiments, said compositions include (a) from about 35% to about 55% by weight of HFC-32; (b) from about 30% to about 55% by weight of HFO-1234ze; and (c) more than about 0% to about 22% by weight of HFC-152a or more than 0% to about 15% by weight of HFC-134a. As with the previous ones, in certain embodiments, component (b) in these compositions comprises, consists essentially of, or consists of HFO-1234ze.

In other embodiments, compositions of the foregoing may include (a) from about 33% to about 55% by weight of HFC-32; (b) from about 25% to about 66% by weight of HFO-1234ze; (c) more than about 0% to about 25% by weight of HFC-152a; and (d) more than about 0% to about 20% by weight of HFC-134a. Even in other embodiments, said compositions include (a) from about 35% to about 55% by weight of HFC-32; (b) from about 20%) to about 60%) by weight of HFO-1234ze; (c) more than about 0% to about 22% by weight of HFC-152a; and (d) more than about 0% to about 15% by weight of HFC-134a. In certain embodiments, component (b) in these compositions comprises, consists essentially of, or consists of HFO-1234ze.

As mentioned before, applicants have found that the compositions of the present invention are capable of achieving a difficult combination of properties, including low GWP. By way of non-limiting example, the following Table A illustrates the substantial superiority of GWP of certain compositions of the present invention, which are described in parentheses in terms of the weight fraction of each component, as compared to the GWP of HFC-22, which has a global warming potential 1810.

Table A Applicants have also surprisingly found that in each of the above embodiments of the invention, particularly though not exclusively where component (b) is HFO-1234ze, then the rate of combustion of the present compositions is substantially linearly related to the Combustion rate averaged by weight of the components according to formula I: BVcomp = å (I in weight of i · BVi) where BVcomp is the combustion speed of the composition, and i is added for each of the components listed above in the composition, and the amounts of each of the components listed above are preferably selected to ensure that BVcomp based on the unexpected finding of this formula is less than about 10, most preferably least that approximately 9 and most preferably still less than about 8, while at the same time, the GWP of the composition is less than about 5.00, less than about 400, or most preferably less than about 350.

As mentioned above, the compositions of the present invention exhibit a degree of hazard value not greater than about 7. As used herein, the degree of hazard is measured by observing the results of a cube test using the composition in question and Applying a value to that test as indicated in the guidelines set forth in the following table.

Danger value guide table The cube test is carried out as indicated in the Examples below.

The compositions of the present invention can include other components for the purpose of improving or providing certain functionality to the composition, or in some cases reducing the cost of the composition. For example, refrigerant compositions in accordance with the present invention, especially those used in vapor compression systems, include a lubricant, generally in amounts of about 30 to about 50 percent by weight of the composition, and in some cases potentially in an amount greater than about 50 percent and other cases in quantities as low as approximately 5 percent.

Commonly used refrigeration lubricants such as polyol esters (POEs) and polyalkylene glycols (PAG), PAG oils, Silicon oil, mineral oil, alkylbenzenes (AB) and poly (alpha-olefin) (PAO) that are used in machinery of refrigeration with refrigerants Hydrofluorocarbon (HFC) can be used with the refrigerant compositions of the present invention. Commercially available mineral oils include Witco LP 250 (registered trademark) from Witco, Zerol 300. (registered trademark) from S.hrieve Química, Sunisco 3GS from Witco, and Calumet R015 from Calumet. Commercially available alkylbenzene lubricants include Zerol 150 (registered trademark). Commercially available asters include neopentyl glycol dipelargonate, which is available as Emery 2917 (registered trademark) and Hatcol 2370 (registered trademark). Other useful esters include phosphate esters, dibasic acid esters, and fluoroesters. In some cases, hydrocarbon-based oils have sufficient solubility with the refrigerant which is composed of an iodocarbon, where the combination of iodocarbon and hydrocarbon oil are more stable than other types of lubricant. Therefore, said combinations are advantageous. Preferred lubricants include polyalkylene glycols and polyalkylene esters. Polyalkylene glycols are very preferred in certain embodiments because they are currently in use in particular applications, such as mobile air-conditioning systems. Of course, different mixtures of different types of lubricants can be used.

Methods and heat transfer systems The present methods, systems and compositions are therefore adaptable to be used in connection with a wide variety of heat transfer systems in general and cooling systems, in particular, such as air conditioning (including both stationary and mobile air conditioning systems), refrigeration (including commercial refrigeration), heat pump systems, and the like. In certain preferred embodiments, the compositions of the present invention are used in refrigeration systems originally designed for use with an HCFC refrigerant, such as, for example, R-22. Preferred compositions of the present invention tend to exhibit many of the desirable characteristics of R-22, but have a GWP that is substantially less than that of R-22, while at the same time having a capacity that is substantially similar to, or substantially coincides, and preferably is as high as or greater than R-22. In particular, applicants have recognized that certain preferred embodiments of the present compositions tend to have relatively low global warming potentials ("GEP"), preferably less than about 500, and most preferably no greater than about 400, and most preferably not yet greater than about 350.

In certain other preferred embodiments, the present compositions are used in refrigeration systems originally designed for use with R-22. Preferred refrigeration compositions of the present invention can be used in refrigeration systems containing a lubricant conventionally used with R-22, such as polyester oils, and the like, or can be used with other lubricants traditionally used with HFC refrigerants. As used herein, the term "cooling system" generally refers to any system or apparatus, or any part or portion of said system or apparatus, that uses a refrigerant to provide cooling. Such air cooling systems include, for example, air conditioning systems, electric refrigerators, chillers, and the like.

Examples The following examples are provided for the purpose of illustrating the present invention, but without limiting the scope thereof.

Example 1: Flammability of the mixtures.

The burn rates of common pure component refrigerants are given in the following Table 1.

Table 1: Combustion rates of pure components The measurements of combustion velocity (BV) for certain mixtures of HFC-152a / 1234ze (E) and HFC-32 / 1234ze (E) are shown in figures 1-2. The combustion rate measurements were carried out using the vertical pipe method described in ISO 817 and the ASHRAE standard 34. Figures 1-2 also show the GWP of the mixtures. The results in Figures 1-2 illustrate the unexpected finding by applicants that the maximum rate of combustion can be approximated by a linear relationship with% by weight of the components. According to certain preferred embodiments, therefore, the amount of the components of the present invention is selected according to Formula I, provided above, that is, by approaching the combustion rate of the mixtures using the speed of Combustion of the pure component in% by weight. In preferred embodiments, the compositions comprise up to about 30% by weight of HFC-152a, most preferably up to 20% of HFC-152a, while still exhibiting a rate of combustion of the mixture that is below about 10 cm / s and that constitutes a 2L refrigerant.

Incidentally, the combustion rate (BV) measurements of the HFC-32 / HFO-1234ze / HFC-152a mixtures were made using the vertical tube method, described in ISO 817 and ASHRAE Standard 34. The results illustrate the unexpected finding that the maximum rate of combustion can be approximated by a linear relationship with the weight% of the components. According to certain preferred embodiments, therefore, the quantity of the components of the present invention is selected according to the formula I provided above, that is, by approximation of the combustion rate of the mixtures using the combustion rate of the pure component in% by weight. In preferred embodiments, the compositions comprise up to about 20% by weight of HFC-152a, while still exhibiting a rate of combustion of the mixture that is below about 10 cm / sec and thus constituting a 2L refrigerant.

As shown in the above data, it has been found that the combustion rate of mixtures according to the present invention can be calculated from the weight% multiplied by the combustion rate of the pure component as described in Formula 1 above.

The rates of combustion of all mixtures from Table A were calculated and are shown below in Table 2. All mixtures have a burn rate of less than 10 cm / s, and therefore would be expected to be classified as A2L refrigerants.

Table 2: Burning speed of the mixtures Example 2: Assessment of danger The cube test is carried out according to the procedure described in this document. Specifically, each material that is being tested is released separately in a clear cube chamber that has an internal volume of 28.32 liters. A low power fan is used to mix the components. An electric spark with sufficient energy is used to ignite the test fluids. The results of all the tests are they record using a video camera. The cube is filled with the composition that is being tested in order to ensure a stoichiometric concentration for each tested refrigerant. The fan is used to mix the components. Efforts are made to ignite the fluid using the spark generator for 1 min. The test is recorded using an HD camcorder.

An outline of the experimental assembly for the test of flammable gases is illustrated in Figure 3.

The hazard index of all the mixtures in Table A is calculated and shown below in Table 3. All mixtures have a hazard rating of less than 7, and therefore are expected to be used safely in air systems conditioned.

Table 3: Dangerousness value of the mixtures With respect to HFC-152a, when used in one or more compositions of the invention, it is important in many applications that the amounts of this component be less than about 20% by weight of the composition and preferably less than 15% by weight . This is demonstrated in Table 3, where 20% of 152a (B3) obtain the hazard value of 6, which is very close to the safety limit of 7.

Example 3: Performance parameters.

The coefficient of performance (COP) is a universally accepted measure of refrigerant performance, especially useful in representing the relative thermodynamic efficiency of a refrigerant in a specific heating or cooling cycle that involves evaporation or condensation of the refrigerant. In refrigeration engineering, this term expresses the ratio of useful cooling to the energy applied by the compressor in the compression of the vapor. The capacity of a refrigerant represents the amount of cooling or heating it provides and provides a measure of the capacity of a compressor to pump quantities of heat for a given volumetric flow of refrigerant. In other words, given a specific compressor, a coolant with a higher capacity will supply more cooling power or heating. One of the means to estimate COP of a refrigerant under specific operating conditions is the thermodynamic properties of the refrigerant using standard refrigeration cycle analysis techniques (see, for example, RC Downing, FLUOROCARBON REFRIGERANTS HANDBOOK, Chapter 3, Prentice-Hall , 1988).

Below is an example of an air conditioning system having the condenser temperature set to 40.55 ° C, which generally corresponds to an outside temperature of about 35 ° C. The degree of sub-cooling at the entrance of the expansion device is adjusted to 5.55 ° C. The evaporation temperature is adjusted to 7 ° C, which corresponds to an indoor ambient temperature of approximately 20 ° C. The degree of overheating at the evaporator outlet is adjusted to 5.55 ° C. The degree of overheating in the suction line is adjusted to 10 ° C, and the efficiency of the compressor is adjusted to 70%. The pressure drop and heat transfer in the connection lines (suction and liquid lines) are considered negligible, and heat leakage through the compressor housing is ignored. Various operating parameters are determined for the compositions identified in Table A above in accordance with the present invention, and these operating parameters are reported in Table 4 below, based on R-22 which has a value COP of 1.00, a capacity value of 1.00 and a discharge temperature of 83.06 ° C.

In certain preferred embodiments, the replacement should not necessitate a substantial redesign of the system and no important element of the equipment needs to be replaced to accommodate the refrigerant of the present invention. For such purpose, the replacement preferably meets one or more of, and preferably all, the following requirements: • High side pressure that is within about 115%, and most preferably still within about 110% of the high side pressure of the same system using R-22. This parameter can be important in these modalities, since it can improve the capacity to use existing pressure components in said systems.

• Discharge temperature that is + 5 ° C of R22. An advantage of said feature is that it can allow the use of existing equipment without activation of the system's thermal protection aspects, which are preferably designed to protect the components of the compressor. This parameter is also advantageous because it can help to avoid the use of expensive controls such as liquid injection to reduce the discharge temperature.

• Cooling capacity that is within + 115% (preferably 110%) and 95% of the cooling capacity of the same system using R-22. This parameter is potentially important in certain modalities because it can help ensure adequate cooling of the product being refrigerated. It should also be borne in mind that excessive capacity can cause an overload of the electric motor so it should also be avoided.

· Efficiency (COP) that is similar to R-22 (± 5%), without incurring excessive capacity as noted above.

• Maintains the degree of overheating of at least + 1 ° C, preferably + 3 ° C. If overheating degrees below 1 ° C are used, there is a risk of liquid return to the compressor.

• The mixture is a class 2L refrigerant with a BV of less than 10 cm / s · The GWP is less than 500, preferably less than 400, and even less than 350 for some of the proposed mixtures.

Table 4 As can be seen from Table 4 above, applicants have found that the compositions of the present invention are capable of achieving at the same time many of the important cooling system performance parameters near the parameters for R-22 and, in particular, narrow enough to allow such compositions to be used as a replacement for R-22 in low temperature cooling systems and / or to be used in existing systems only with minor system modifications.

As shown above, the compositions exhibit capabilities in this low temperature refrigeration system that are within approximately 8% of the capacity of said R-22 system. As has also been demonstrated, all the tested mixtures presented an acceptable performance that is preferred by the fulfillment of all the requirements.

Since many existing air conditioning systems have been designed for R-22, those skilled in the art will appreciate the substantial advantage of a cooler with low GWP and higher efficiency, which can be used as a replacement for R-22 or similar refrigerants with relatively modified minimum to the system. In addition, those skilled in the art will appreciate that the present compositions are capable of providing substantial advantage for Used in new or redesigned refrigeration systems, preferably including air conditioning systems.

Example 4: Sensitivity analysis.

Using the same operating conditions of Example 3, the inventors herein generated data for lower and higher amounts of R32 as shown in Table 5. For each group, they took a representative mixture (A2, B2, C2 and D2). ) and increased / decreased the content of R32 until one of the environmental effects of the performance parameters is outside the preferred range (see example 3).

Table 5 Table 6 Table 7 When it comes to BV and the level of danger, the amount of R32 or 1234ze does not impose any special limitation (tables 6 and 7).

Table 8 Binary mixes of R32 / 1234ze have a GWP preferred of less than 350 so the inventors hereby chose A2 to perform this analysis. At the lower limit of R32, they noticed that the capacity is at the limit of the preferred value (95%). In addition, they did not obtain any degree of overheating when the same expansion device was used. For the high interval of R32, they obtained an excess capacity (116%), which can cause electric motor overload. On the other hand, the GWP of this mixture is 374 which exceeds the preferred limit of 350 (Table 5).

The ternary mixtures of R32 / 1234ze / R152a have a preferred GWP of less than 350 so the inventors hereby chose B2 to perform this analysis. At the lower limit of R32, they noticed that the capacity is at the limit of the preferred value (95%). In addition, they did not obtain any degree of overheating when the same expansion device was used. For the high interval of R32, they obtained an excess capacity (114%), which can cause electric motor overload. On the other hand, the GWP of this mixture is 392 which exceeds the preferred limit of 350 (Table 5).

The ternary mixtures of R32 / 1234ze / R134a have a preferred GWP of less than 400 whereby the inventors hereby chose C2 to perform this analysis. In the lower limit R32, they noticed that the capacity is in the limit of the preferred value (95%). In addition, they did not obtain any degree of overheating when the same expansion device was used. For the high interval of R32, they obtained an excess capacity (117%), which can cause electric motor overload. On the other hand, the GWP of this mixture is 459 which exceeds the preferred limit of 400 (Table 5).

The quaternary mixtures of R32 / 1234ze / R152a / R134a have a preferred GWP of less than 500 so the inventors hereby chose D2 to perform this analysis. At the lower limit R32, they noticed that the capacity is at the limit of the preferred value (95%). In addition, they did not obtain any degree of overheating when the same expansion device was used. For the high interval of R32, they obtained an excess capacity (116%), which can cause electric motor overload. On the other hand, the GWP of this mixture is 557 which exceeds the preferred limit of 500 (table 5).

Example 5: Performance in stationary refrigeration (commercial refrigeration) - applications at medium temperature The performance of some preferred compositions was evaluated against other refrigerant compositions under typical conditions of medium temperature refrigeration.

This application covers refrigeration of fresh foods. The conditions in which the compositions were evaluated are shown in Table 9: Table 9 Table 10 compares the compositions of interest with the baseline refrigerant, R-22 in typical application at medium temperature.

Table 10 As can be seen, the compositions are within 5% of the efficiency of the baseline refrigerant, R-22 and within 5% of capacity.

Example 6 - Performance in stationary refrigeration (commercial refrigeration) - low temperature applications The performance of some preferred compositions was evaluated against other refrigerant compositions under typical conditions of low temperature refrigeration. This application covers the refrigeration of frozen foods. The conditions in which the compositions were evaluated are shown in Table 11: Table 11 Table 12 compares compositions of interest with the reference refrigerant, R-22 in typical application at low temperature.

Table 12 As can be seen, the compositions are within 5% of the efficiency of the baseline refrigerant, R-22 and within 10% of the capacity.

Claims (10)

1. A heat transfer composition having a burn rate of less than about 10 cm / s, a global warming potential of less than about 500 and a capacity in low temperature cooling systems that is within approximately 10% of the cooling capacity of R-22, said composition comprising: (a) from about 33% to about 55% by weight of HFC-32; (b) at least about 25% by weight of HFO-1234ze; Y (c) from more than about 0% to about 30% by weight of HFC-152a, HFC-134a, and combinations thereof, provided that the amount of each of the components (a), (b) and (c) is selected to ensure that the combustion rate of the composition is less than about 10, the overall heating potential of the composition is less than about 500, and its capacity is within about 10% of the refrigeration capacity of R-22 .

2. The heat transfer composition according to claim 1, wherein the component (b) further comprises at least one compound, other than HFO-1234ze, selected from unsaturated propenes terminated in -CF3, unsaturated butenes terminated in -CF3, and combinations thereof.

3. The heat transfer composition according to claim 1, comprising from about 33% to about 55% by weight of HFC-32; from about 25 to about 66% by weight of HFO-1234ze; and from more than about 0% to about 25% by weight of HFC-152a.

4. The heat transfer composition according to claim 3, comprising from about 35% to about 55% by weight of HFC-32; from about 30 to about 55 by weight of HFO-1234ze; and from more than about 0% to about 22% by weight of HFC-152a.

5. The heat transfer composition according to claim 4, comprising from about 35% to about 55% by weight of HFC-32; component; from about 30 to about 55% by weight of HFO-1234ze; and from about 5% to about 22% by weight of HFC-152a.

6. The heat transfer composition according to claim 1, comprising from about 33% to about 55% by weight of HFC-32; from about 45 to about 66% by weight of HFO- 1234ze; and from more than about 0% to about 20% by weight of HFC-134a.

7. The heat transfer composition according to claim 1, comprising from about 33% to about 55% by weight of HFC-32; component; from about 25 to about 66% by weight of HFO-1234ze; and from more than about 0% to about 20% by weight of HFC-134a and from more than about 0% to about 25% by weight of HFC-152a, wherein the total amount of HFC-134a and HFC-152a does not exceed of 30% by weight.

8. A method of replacing an existing heat transfer fluid contained in the heat transfer system comprising removing at least a portion of said heat transfer fluid from said system, the existing heat transfer fluid being HFC- 22 and replacing at least a portion of said existing said heat transfer fluid by introducing into said system a heat transfer composition of any of claims 1-7.

9. A heat transfer system comprising a compressor, a condenser and an evaporator in fluid communication, and a heat transfer composition in said system, said liquid transfer composition. heat comprising the composition of any of claims 1-7.

10. A method of transferring heat to or from a fluid or body comprising causing a phase change in a composition of any of claims 1-7, and exchanging heat with said fluid or body during the phase change. SUMMARY OF THE INVENTION Compositions and methods of heat transfer that include (a) HFC-32; (b) HFO-1234ze, and (c) either or both of HFC-152a and / or HFC-134a.