EP2807226A1

EP2807226A1 - Heat transfer compositions having improved miscibility with lubricating oil

Info

Publication number: EP2807226A1
Application number: EP13701847.9A
Authority: EP
Inventors: Sophie GUERIN; Wissam Rached
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2012-01-25
Filing date: 2013-01-09
Publication date: 2014-12-03
Also published as: FR2986007B1; JP2015506402A; KR20140107611A; CN104066809A; JP5933758B2; CN104066809B; US8858825B2; WO2013110868A1; US20130186114A1; FR2986007A1

Abstract

The invention relates to a composition comprising: - a heat transfer fluid comprising from 15% to 30% of ammonia and from 70% to 85% of 2,3,3,3-tetrafluoropropene; and - a lubricating oil comprising polyalkylene glycol. The invention also relates to the use of ammonia for increasing the miscibility of 2,3,3,3-tetrafluoropropene with the polyalkylene glycol and vice versa.

Description

HEAT TRANSFER COMPOSITIONS HAVING IMPROVED MISCIBILITY WITH LUBRICATING OIL

FIELD OF THE INVENTION

The present invention relates to 2,3,3,3-tetrafluoropropene-based heat transfer compositions having improved miscibility with the lubricating oil. TECHNICAL BACKGROUND

Fluorocarbon-based fluids are widely used in vapor compression heat transfer systems, including air conditioning, heat pump, refrigeration or freezing devices. These devices have in common to rely on a thermodynamic cycle comprising the vaporization of the fluid at low pressure (in which the fluid absorbs heat); compressing the vaporized fluid to a high pressure; condensing the vaporized fluid into a high pressure liquid (in which the fluid emits heat); and the expansion of the fluid to complete the cycle.

The choice of a heat transfer fluid (which may be a pure compound or a mixture of compounds) is dictated on the one hand by the thermodynamic properties of the fluid, and on the other hand by additional constraints. Thus, a particularly important criterion is that of the impact of the fluid considered on the environment. In particular, chlorinated compounds (chlorofluorocarbons and hydrochlorofluorocarbons) have the disadvantage of damaging the ozone layer. Thus, non-chlorinated compounds such as hydrofluorocarbons, fluoroethers and fluoroolefins are now generally preferred.

Another environmental constraint is that of global warming potential (GWP). It is therefore essential to develop heat transfer compositions with as low a GWP as possible and good energy performance. In addition, to lubricate the moving parts of the compressor (or compressors) of a vapor compression system, a lubricating oil must be added to the heat transfer fluid. The oil can be generally mineral or synthetic.

The choice of the lubricating oil is made according to the type of compressor, and so as not to react with the heat transfer fluid itself and with the other compounds present in the system.

For some heat transfer systems (especially small ones), the lubricating oil is generally allowed to circulate throughout the circuit, the piping being designed so that the oil can flow by gravity to the compressor. In other heat transfer systems (especially large ones), an oil separator is provided immediately after the compressor as well as an oil level control device, ensuring a return of the oil to the or the compressors. Even when an oil separator is present, the system piping must still be designed so that the oil can return by gravity to the oil separator or the compressor.

The document WO 2004/037913 describes compositions based on fluoroolefins and especially based on tetrafluoropropene or pentafluoropropene. In Example 2 is reported the miscibility of 1,2,3,3,3-pentafluoropropene (HFO-1225ye) with various lubricating oils, as well as that of 1, 3,3,3-tetrafluoropropene (HFO-1234ze) with various lubricating oils. In Example 3 is reported the compatibility of HFO-1234ze and 3,3,3-trifluoropropene (HFO-1243zf) with lubricating oils of the polyalkylene glycol type.

WO 2005/042663 is specifically concerned with the miscibility of mixtures of fluorolefins and lubricating oils. The examples provided for these mixtures are essentially the same as those of WO 2004/037913.

WO 2006/094303 describes a large number of heat transfer compositions comprising fluorolefins, and in particular 2,3,3,3-tetrafluoropropene (HFO-1234yf), and additional compounds. In addition, the document generally teaches combining the list of many possible refrigerants with a list of lubricating oils.

WO 2007/126414 describes a large number of mixtures of heat transfer compounds, including mixtures comprising 2,3,3,3-tetrafluoropropene (HFO-1234yf) and ammonia. The document teaches also to add any lubricant selected from a list of conventional lubricants.

WO 2008/009928 and WO 2008/009922 disclose heat transfer compositions based on pentafluoropropene, tetrafluoropropene and at least one additional compound, which may be ammonia.

Document US 2006/0243945 describes a large number of mixtures of heat transfer compounds, and in particular quaternary compositions based on HFO-1234yf, ammonia, difluoromethane (HFC-32) and trifluoroiodomethane. A generic list of possible lubricants is cited.

When the heat transfer compound (s) exhibit poor miscibility with the lubricating oil, the latter tends to be trapped at the evaporator and not to return to the compressor, which does not allow correct operation. of the system.

In this respect, there is still a need to develop low GWP (and good energy performance) heat transfer compositions in which the heat transfer compounds exhibit good miscibility with the lubricating oil.

In particular, the HFO-1234yf is a very interesting heat transfer compound due in particular to its low GWP and its good energy performance. On the other hand, its miscibility with certain lubricating oils such as polyalkylene glycol oils is imperfect and limits its application. It is therefore desirable to improve the miscibility of compositions based on HFO-1234yf with the usual lubricating oils.

SUMMARY OF THE INVENTION

The invention firstly relates to a composition comprising:

a heat transfer fluid comprising from 15 to 30% of ammonia and from 70 to 85% of 2,3,3,3-tetrafluoropropene; and a lubricating oil comprising polyalkylene glycol.

According to one embodiment, the heat transfer fluid consists of a mixture of ammonia and 2,3,3,3-tetrafluoropropene.

According to one embodiment, the heat transfer fluid comprises from 18 to 26% of ammonia and from 74 to 82% of 2,3,3,3-tetrafluoropropene, preferably from 21 to 23% of ammonia and from 77 to 79% 2,3,3,3-tetrafluoropropene. According to one embodiment, the lubricating oil consists of polyalkylene glycol.

According to one embodiment, the lubricating oil represents from 1 to 99%, preferably from 5 to 50%, more preferably from 10 to 40%, and preferably from 15 to 35%, of the composition.

According to one embodiment, the composition further comprises one or more additives chosen from heat transfer compounds, stabilizers, surfactants, tracer agents, fluorescent agents, odorants, solubilizing agents and mixtures thereof.

The invention also relates to the use of polyalkylene glycol as a lubricating oil in a vapor compression circuit, in combination with a heat transfer fluid comprising 15 to 30% ammonia and 70 to 85% 2,3,3,3-tetrafluoropropene.

According to one embodiment, the polyalkylene glycol is used in a proportion of 1 to 99%, preferably 5 to 50%, more preferably 10 to 40%, and ideally 15 to 35%, relative to sum of the polyalkylene glycol and the heat transfer fluid.

According to one embodiment, the heat transfer fluid comprises from 18 to 26% of ammonia and from 74 to 82% of 2,3,3,3-tetrafluoropropene, preferably from 21 to 23% of ammonia and from 77 to 79% 2,3,3,3-tetrafluoropropene.

The invention also relates to a heat transfer installation comprising a vapor compression circuit containing a heat transfer composition which is a composition as described above.

According to one embodiment, the installation is chosen from mobile or stationary heat pump heating, air conditioning, refrigeration, freezing and Rankine cycles.

According to one embodiment, the installation is an automotive air conditioning installation.

The invention also relates to a method for heating or cooling a fluid or a body by means of a vapor compression circuit containing a heat transfer fluid, said method comprising successively at least partial evaporation of the heat transfer fluid, the compression of the heat transfer fluid, the at least partial condensation of the heat transfer fluid and the expansion of the heat transfer fluid. heat transfer, wherein the heat transfer fluid is associated with a lubricating oil to form a heat transfer composition, said heat transfer composition being a composition as described above.

The invention also relates to a method for reducing the environmental impact of a heat transfer installation comprising a vapor compression circuit containing an initial heat transfer fluid, said method comprising a step of replacing the heat transfer fluid. initial heat in the vapor compression circuit by a final heat transfer fluid, the final heat transfer fluid having a GWP lower than the initial heat transfer fluid, wherein the final heat transfer fluid is associated with a lubricating oil for forming a heat transfer composition, said heat transfer composition being a composition as described above.

The invention also relates to the use of ammonia to increase the miscibility of 2,3,3,3-tetrafluoropropene with a lubricating oil.

According to one embodiment, the ammonia is used in a proportion of 15 to 30%, preferably 18 to 26%, and more preferably 21 to 23%, relative to the sum of the ammonia and the ammonia. 2,3,3,3-tetrafluoropropene.

The invention also relates to the use of 2,3,3,3-tetrafluoropropene to increase the miscibility of ammonia with a lubricating oil.

According to one embodiment, 2,3,3,3-tetrafluoropropene is used in a proportion of 70 to 85%, preferably 74 to 82%, more preferably 77 to 79%, relative to the sum ammonia and 2,3,3,3-tetrafluoropropene.

According to one embodiment, the lubricating oil comprises, preferably consists of polyalkylene glycol.

The invention also relates to a kit comprising:

a heat transfer fluid comprising from 15 to 30% of ammonia and from 70 to 85% of 2,3,3,3-tetrafluoropropene on the one hand;

a lubricating oil comprising a polyalkylene glycol on the other hand;

for use in a heat transfer installation comprising a vapor compression circuit.

The invention also relates to a kit comprising: - ammonia;

2,3,3,3-tetrafluoropropene;

a lubricating oil comprising a polyalkylene glycol on the other hand;

the amount of ammonia being 15 to 30% and the amount of 2,3,3,3-tetrafluoropropene being 70 to 85%, relative to the sum of ammonia and 2,3,3,3- tetrafluoropropene, for use in a heat transfer plant comprising a vapor compression circuit.

According to one embodiment, the lubricating oil consists of polyalkylene glycol.

According to one embodiment, the kits above are for use in a car air conditioning installation.

The present invention makes it possible to meet the needs felt in the state of the art. More particularly, it provides low GWP heat transfer compositions having good energy performance, and wherein the heat transfer compounds exhibit good miscibility with the lubricating oil.

In particular, the invention provides HFO-1234yf heat transfer compositions having improved miscibility with polyalkylene glycol based lubricating oils.

This is accomplished by mixing HFO-1234yf with ammonia (NH ₃ ). Thus, the present inventors have found that ammonia improves the miscibility properties of HFO-1234yf with polyalkylene glycols, and especially at temperatures above 25 ° C.

The polyalkylene glycol type oils have good lubricity, low pour point, good low temperature fluidity, and good compatibility with elastomers generally present in a vapor compression circuit. They are also relatively less expensive than other lubricating oils and they are oils whose use is currently very widespread in certain fields, and particularly in the field of automotive air conditioning. It is therefore very advantageous to improve the miscibility of HFO-1234yf with a polyalkylene glycol type lubricating oil, so that this heat transfer compound can be used to a greater extent in combination with this lubricating oil, especially without use mechanical techniques to ensure the return of oil in the compressors. Conversely, it has been found that HFO-1234yf improves the miscibility properties of ammonia with polyalkylene glycols, and especially at temperatures below 30 ° C.

Ammonia and HFO-1234yf therefore have synergistic properties with respect to miscibility with polyalkylene glycols.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph showing the threshold temperature of immiscibility of HFO-1234yf with a polyalkylene glycol oil (in ° C, ordinate), as a function of the relative proportion of oil in HFO-1234yf (in%, on the abscissa).

FIG. 2 is a graph showing the immiscibility threshold temperature of the ammonia with a polyalkylene glycol oil (in ° C, ordinate), as a function of the relative proportion of oil in ammonia (in%, in abscissa).

FIG. 3 is a graph showing the upper and lower threshold temperatures of immiscibility of an HFO-1234yf / ammonia mixture with a polyalkylene glycol oil (in ° C, ordinate), as a function of the relative proportion of oil in the mixture HFO-1234yf / ammonia (in%, abscissa).

On these graphs, the miscibility zone is denoted M, and the immiscibility zone is denoted NM.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now described in more detail and without limitation in the description which follows.

Unless otherwise stated, in the whole of the application the proportions of compounds indicated are given in percentages by mass.

According to the present application, the global warming potential (GWP) is defined with respect to the carbon dioxide and with respect to a duration of 100 years, according to the method indicated in "The scientific assessment of ozone depletion, 2002, a report of the World Meteorological Association's Global Ozone Research and Monitoring Project.

By "heat transfer compound" or "heat transfer fluid" (or refrigerant), is meant a compound, respectively a fluid, capable of absorbing heat by evaporating at low temperature and low pressure and to reject heat by condensing at high temperature and high pressure, in a vapor compression circuit. In general, a heat transfer fluid may comprise one, two, three or more than three heat transfer compounds.

By "heat transfer composition" is meant a composition comprising a heat transfer fluid and optionally one or more additives which are not heat transfer compounds for the intended application.

The invention relies on the use of two heat transfer compounds, namely HFO-1234yf and ammonia, and a lubricating oil, to form a heat transfer composition.

The heat transfer composition can be introduced as such into a vapor compression circuit. Alternatively, the heat transfer fluid (comprising HFO-1234yf and ammonia) and the lubricating oil, at the same point or not, can be introduced separately into the circuit. The individual heat transfer compounds (HFO-1234yf and ammonia) can also be introduced separately.

The lubricating oil is preferably of the polyalkylene glycol type. For the purposes of the invention, the polyalkylene glycol may comprise polyalkylene glycols of different formulas in a mixture.

In general, the polyalkylene glycol suitable for use in the context of the invention comprises from 5 to 50 repeating oxyalkylene units, each containing from 1 to 5 carbon atoms.

The polyalkylene glycol may be linear or branched. It may be a homopolymer or a copolymer of 2, 3 or more groups selected from oxyethylene, oxypropylene, oxybutylene, oxypentylene and combinations thereof.

Preferred polyalkylene glycols comprise at least 50% oxypropylene groups.

Suitable polyalkylene glycols are described in US

4.971, 712. Other suitable polyalkylene glycols are the polyalkylene glycols having hydroxyl groups at each end, as described in US Pat. No. 4,755,316. Other suitable polyalkylene glycols are the polyalkylene glycols having a capped hydroxyl end. The hydroxyl group may be capped with an alkyl group containing from 1 to 10 carbon atoms (and optionally containing one or more heteroatoms such as nitrogen), or a fluoroalkyl group containing heteroatoms such as nitrogen, or a fluoroalkyl group as described in US 4,975,212, or other similar groups.

When the two hydroxyl ends of the polyalkylene glycol are capped, one can use the same end group or a combination of two distinct groups.

The terminal hydroxyl groups may also be capped to form an ester with a carboxylic acid, as described in US 5,008,028. The carboxylic acid can also be fluorinated.

When both ends of the polyalkylene glycol are capped, one or the other may be an ester, or one end may be capped with an ester and the other end be free or capped with one of the aforementioned alkyl, heteroalkyl or fluoroalkyl groups.

Polyalkylene glycols suitable for use as lubricating oils and commercially available are, for example, General Motors Goodwrench Oils, Daimler-Chrysler MOPAR-56, Shrieve Chemical Products Zerol, Total's Planetelf PAG and Daphne Hermetic PAG. Itemitsu. Other suitable polyalkylene glycols are made by Dow Chemical and Denso. Mention may also be made of oils manufactured by Fuchs and in particular RENISO PG 68 / NH3 oil.

The viscosity of the polyalkylene glycol may for example be from 1 to 1000 centistokes at 40 ° C, preferably from 10 to 200 centistokes at 40 ° C and more preferably from 30 to 80 centistokes at 40 ° C.

The viscosity is determined according to ISO viscosity grades, according to ASTM D2422.

The oil marketed by Denso under the name ND8, having a viscosity of 46 centistokes, is particularly suitable.

The proportion of lubricating oil to be used in combination with the heat transfer fluid depends mainly on the type of installation concerned. Indeed, the total quantity of lubricating oil in the installation depends mainly on the nature of the compressor, while the total amount of heat transfer fluid in the installation depends mainly on the exchangers and the piping.

In general, the proportion of lubricating oil in the heat transfer composition, or in other words in relation to the sum of the lubricating oil and the heat transfer fluid, is from 1 to 99%, preferably from 5 to 50%, for example 10 to 40% or 15 to 35%. According to a particular embodiment, the lubricating oil used consists of the polyalkylene glycol described above, with the exception of any other lubricating compound.

According to an alternative embodiment, another lubricating oil is used in combination with the polyalkylene glycol. It may especially be chosen from mineral oils, silicone oils, paraffins of natural origin, naphthenes, synthetic paraffins, alkylbenzenes, poly-alpha olefins, polyol esters and / or polyvinyl ethers. . Polyol esters and polyvinyl ethers are preferred. When another lubricating oil is used in combination with the polyalkylene glycol, it is desirable that the miscibility of HFO-1234yf and / or ammonia with this oil is greater than the miscibility of HFO-1234yf and / or ammonia with polyalkylene glycol.

The heat transfer compounds mainly used in the context of the present invention are HFO-1234yf and ammonia.

However, the heat transfer compositions according to the invention may optionally comprise one or more additional heat transfer compounds, besides HFO-1234yf and ammonia. These additional heat transfer compounds may be chosen especially from hydrocarbons, hydrofluorocarbons, ethers, hydrofluoroethers and fluoroolefins.

According to particular embodiments, the heat transfer fluids according to the invention may be ternary (consisting of three heat transfer compounds) or quaternary (consisting of four heat transfer compounds) compositions, in association with the lubricating oil for forming the heat transfer compositions according to the invention.

However, binary heat transfer fluids are preferred.

By binary fluid is meant either a fluid consisting of a mixture of HFO-1234yf and ammonia; is a fluid consisting essentially of a mixture of HFO-1234yf and ammonia, but may contain impurities in a proportion of less than 1%, preferably less than 0.5%, preferably less than 0.1%, preferably less than 0.05% and preferably less than 0.01%.

According to particular embodiments, the proportion of HFO-1234yf in the heat transfer fluid may be: 0.1 to 5%; or 5 to 10%; or 10 to 15%; or 15 to 20%; or from 20 to 25%; or 25 to 30%; or from 30 to 35%; or 35 to 40%; or 40 to 45%; or 45 to 50%; or 50 to 55%; or 55 to 60%; or from 60 to 65%; or from 65 to 70%; or 70 to 75%; or from 75 to 80%; or from 80 to 85%; or from 85 to 90%; or from 90 to 95%; or 95 to 99.9%.

According to particular embodiments, the proportion of ammonia in the heat transfer fluid may be: 0.1 to 5%; or 5 to 10%; or 10 to 15%; or 15 to 20%; or from 20 to 25%; or 25 to 30%; or from 30 to 35%; or 35 to 40%; or 40 to 45%; or 45 to 50%; or 50 to 55%; or 55 to 60%; or from 60 to 65%; or from 65 to 70%; or 70 to 75%; or from 75 to 80%; or from 80 to 85%; or from 85 to 90%; or from 90 to 95%; or 95 to 99.9%.

The values given in the previous three paragraphs apply to the heat transfer fluid without the lubricating oil, and not to the heat transfer composition which comprises the heat transfer fluid, the lubricating oil and optionally other additives.

It may be preferable not to have a too high proportion of NH ₃ in the mixture, as part of a use as a heat transfer fluid, in order to avoid a too high temperature rise at the outlet of the compressor .

Of the above heat transfer fluids, some have the advantage of being azeotropic or near-azeotropic. For example, it has been found that the azeotrope for the binary mixture HFO-1234yf / NH ₃ is obtained for a proportion of NH ₃ of about 23% (± 2%), at a temperature of 5 ° C.

(± 1 ° C) and at a pressure of 7.3 bar (± 1 bar).

The term "quasi-azeotropic" refers to those compositions for which, at a constant temperature, the liquid saturation pressure and the vapor saturation pressure are almost identical (the maximum pressure difference being 10%, or even advantageously 5%, relative to at the liquid saturation pressure).

For "azeotropic" compositions, at a constant temperature, the maximum pressure difference is close to 0%.

These heat transfer fluids have the advantage of ease of implementation. In the absence of significant temperature slippage, there is no significant change in the circulating composition, and no significant change in composition in case of leakage.

In addition, it has been found that certain compositions according to the invention have improved performance compared with R404A (a mixture of 52

% 1,1,1-trifluoroethane, 44% pentafluoroethane and 4% 1,1,1,2-tetrafluoroethane) and / or R410A (50% difluoromethane / 50% mixture). % pentafluoroethane), in particular for moderate temperature cooling processes, that is to say those in which the temperature of the cooled fluid or body is -15 ° C to 15 ° C, preferably -10 ° C. ° C to 10 ° C, more preferably from -5 ° C to 5 ° C (ideally about 0 ° C). In this regard, the compositions for which the proportion of NH ₃ is greater than or equal to 15% are particularly preferred, especially the compositions having a proportion of NH ₃ of 15 to 30%, preferably 18 to 26%.

It has also been found that certain compositions according to the invention have improved performances compared with R410A, in particular for processes of heating at moderate temperature, that is to say those in which the temperature of the fluid or of the heated body is from 30 ° C to 80 ° C, and preferably from 35 ° C to 55 ° C, more preferably from 40 ° C to 50 ° C (most preferably about 45 ° C). In this respect, the compositions for which the proportion of NH ₃ is greater than or equal to 15% are particularly preferred, especially compositions having a proportion of NHs of 20 to 30%.

The other additives that may be used in the context of the invention may especially be chosen from stabilizers, surfactants, tracer agents, fluorescent agents, odorants and solubilizing agents.

The stabilizer (s), when present, preferably represent at most 5% by weight in the heat transfer composition. Among the stabilizers, there may be mentioned in particular nitromethane, ascorbic acid, terephthalic acid, azoles such as azole tolut or benzotriazole, phenol compounds such as tocopherol, hydroquinone, t-butyl hydroquinone, 2,6-di-tert-butyl-4-methylphenol, epoxides (optionally fluorinated or perfluorinated alkyl or alkenyl or aromatic) such as n-butylglycidyl ether, hexanedioldiglycidyl ether, allylglycidyl ether, butylphenylglycidyl ether, phosphites, phosphonates thiols and lactones.

As tracer agents (which can be detected) mention may be made of deuterated or non-deuterated hydrofluorocarbons, deuterated hydrocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodinated compounds, alcohols, aldehydes, ketones, nitrous oxide and combinations thereof. The tracer agent is different from the one or more heat transfer compounds composing the heat transfer fluid. As solubilizing agents, mention may be made of hydrocarbons, dimethyl ether, polyoxyalkylene ethers, amides, ketones, nitriles, chlorocarbons, esters, lactones, aryl ethers, fluoroethers and magnesium compounds. 1-trifluoroalkanes. The solubilizing agent is different from the one or more heat transfer compounds composing the heat transfer fluid.

As fluorescent agents, mention may be made of naphthalimides, perylenes, coumarins, anthracenes, phenanthracenes, xanthenes, thioxanthenes, naphthoxanhthenes, fluoresceins and derivatives and combinations thereof.

As odorants, mention may be made of alkyl acrylates, allyl acrylates, acrylic acids, acrylresters, alkyl ethers, alkyl esters, alkynes, aldehydes, thiols, thioethers, disulfides, allyl isothiocyanates and alkanoic acids. , amines, norbornenes, norbornene derivatives, cyclohexene, heterocyclic aromatic compounds, ascaridole, o-methoxy (methyl) phenol and combinations thereof.

The heat transfer method according to the invention is based on the use of an installation comprising a vapor compression circuit which contains a heat transfer composition (i.e. a heat transfer fluid and at least one lubricating oil ). The heat transfer process may be a method of heating or cooling a fluid or a body.

The vapor compression circuit includes at least one evaporator, a compressor, a condenser and an expander, and fluid transport lines between these elements. The evaporator and the condenser comprise a heat exchanger allowing a heat exchange between the heat transfer fluid and another fluid or body.

As a compressor, it is possible to use in particular a centrifugal compressor with one or more stages or a mini centrifugal compressor. Rotary, piston or screw compressors can also be used. The compressor may be driven by an electric motor or by a gas turbine (eg powered by vehicle exhaust, for mobile applications) or by gearing.

The facility may include a turbine to generate electricity (Rankine cycle).

The installation may also possibly comprise at least one coolant circuit used to transmit the heat (with or without change of state) between the heat transfer fluid circuit and the fluid or body to be heated or cooled.

The installation may also optionally include two or more vapor compression circuits containing identical or different heat transfer fluids. For example, the vapor compression circuits may be coupled together.

The vapor compression circuit operates in a conventional vapor compression cycle. The cycle comprises changing the state of the heat transfer fluid from a liquid phase (or two-phase liquid / vapor) to a vapor phase at a relatively low pressure, and then compressing the fluid in the vapor phase to a relatively high pressure. high, the change of state (condensation) of the heat transfer fluid from the vapor phase to the liquid phase at a relatively high pressure, and the reduction of the pressure to restart the cycle.

In the case of a cooling process, heat from the fluid or the body that is cooled (directly or indirectly, via a coolant) is absorbed by the heat transfer fluid, during the evaporation of the latter, and this at a relatively low temperature compared to the environment. Cooling processes include air conditioning processes (with mobile installations, for example in vehicles, or stationary), refrigeration and freezing or cryogenics.

In the case of a heating process, heat is transferred (directly or indirectly via a heat transfer fluid) from the heat transfer fluid, during the condensation thereof, to the fluid or to the body that is heating, and this at a relatively high temperature compared to the environment. The installation for implementing the heat transfer is called in this case "heat pump".

It is possible to use any type of heat exchanger for the implementation of heat transfer fluids according to the invention, and in particular co-current heat exchangers or, preferably, heat exchangers against -current. It is also possible to use microchannel exchangers.

The invention makes it possible in particular to implement cooling processes at a moderate temperature, that is to say in which the temperature of the cooled fluid or body is from -15 ° C. to 15 ° C., preferably from -10 ° C to 10 ° C, more preferably from -5 ° C to 5 ° C (most preferably about 0 ° C).

The invention also makes it possible to implement heating processes at a moderate temperature, that is to say in which the temperature of the fluid or of the heated body is from 30 ° C. to 70 ° C., and preferably 35 ° C. C at 55 ° C, more preferably at 40 ° C to 50 ° C (most preferably at about 45 ° C).

In the processes of "cooling or heating at moderate temperature" mentioned above, the inlet temperature of the heat transfer fluid to the evaporator is preferably from -20 ° C. to 10 ° C., especially from -15 ° C. ° C at 5 ° C, more preferably at -10 ° C to 0 ° C and for example about -5 ° C; and the temperature of the start of condensation of the heat transfer fluid at the condenser is preferably 25 ° C to 80 ° C, especially 30 ° C to 70 ° C, more preferably 35 ° C to 55 ° C C and for example about 50 ° C. These processes may be refrigeration, air conditioning or heating processes.

According to a preferred embodiment, the heat transfer fluid is during the entire cycle at a temperature at which it is miscible with the lubricating oil. For example, the heat transfer fluid is during the entire cycle at a temperature between -20 ° C and 70 ° C.

It should be noted that the addition of ammonia in a heat transfer fluid consisting of HFO-1234yf (or comprising HFO-1234yf) improves the miscibility of the heat transfer fluid with the lubricating oil, in that it increases the threshold temperature of appearance of the immiscibility zone (defined, for HFO-1234yf, as the temperature above which the liquid-phase compounds form an emulsion), and thus makes it possible to increase the possibilities for using the heat transfer fluid, for example with use at a higher condensing temperature.

Conversely, the addition of HFO-1234yf in a heat transfer fluid consisting of ammonia (or ammonia) improves the miscibility of the heat transfer fluid with the lubricating oil, i.e. say decreases the threshold temperature of appearance of the immiscibility zone (defined for ammonia as the temperature below which the liquid-phase compounds form an emulsion), and therefore increases the possibilities use of the heat transfer fluid, for example with use at a lower evaporation temperature. More generally, the invention makes it possible to proceed to the replacement of any heat transfer fluid in all heat transfer applications, and for example in automobile air conditioning. For example, the heat transfer fluids and heat transfer compositions according to the invention can serve to replace:

1,1,1,2-tetrafluoroethane (R134a);

1,1-Difluoroethane (R152a);

1,1,1,3,3-pentafluoropropane (R245fa);

mixtures of pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a) and isobutane (R600a), namely R422;

chlorodifluoromethane (R22);

the mixture of 51.2% chloropentafluoroethane (R 15) and 48.8% chlorodifluoromethane (R 22), namely R 502;

- any hydrocarbon;

the mixture of 20% of difluoromethane (R32), 40% of pentafluoroethane (R125) and 40% of 1, 1, 1, 2-tetrafluoroethane (R134a), namely R407A;

the mixture of 23% of difluoromethane (R32), 25% of pentafluoroethane (R125) and 52% of 1, 1, 1, 2-tetrafluoroethane (R134a), namely R407C;

the mixture of 30% of difluoromethane (R32), 30% of pentafluoroethane (R125) and 40% of 1,1,1,2-tetrafluoroethane (R134a), namely R407F;

R1234yf (2,3,3,3-tetrafluoropropene);

R1234ze (1, 3,3,3-tetrafluoropropene).

EXAMPLE

The following example illustrates the invention without limiting it.

In this example, the miscibility of HFO-1234yf, ammonia, and the azeotropic mixture of HFO-1234yf and ammonia with a polyalkylene glycol (PAG) ND8 lubricating oil is studied.

An autoclave is placed in a glass vat, fed by a thermostatic bath of water or brine according to the test temperatures, from -30 ° C to + 80 ° C.

For each experiment, the heat transfer fluid is introduced into the autoclave. Then a first quantity of defined lubricating oil is added, and the mixture is stirred. We increase the temperature within the autoclave until an emulsion is obtained, signaling the non-miscibility of the mixture. Then the mixture is cooled, an additional amount of oil is introduced into the mixture, and iteratively is carried out.

This step makes it possible to plot, for each transfer fluid, a curve making it possible to visualize the zone of non-miscibility of the mixture with the oil PAG, as a function of the temperature.

The results are shown in Fig. 1 for pure HFO-1234yf, in Fig. 2 for pure ammonia, and in Fig. 3 for the 78% azeotropic mixture of HFO-1234yf. 1234yf and 22% ammonia.

A good miscibility of the oil in HFO-1234yf at low temperatures is observed, with, on the other hand, a large zone of immiscibility at temperatures above 25 ° C.

A good miscibility of the oil in ammonia at high temperatures is observed, with, on the other hand, a large non-miscibility zone at temperatures below 30 ° C.

The azeotropic mixture HFO-1234yf / NH ₃ has an improved miscibility with the oil, up to a temperature higher than 70 ° C. At very low temperatures (below about -20 ° C), the mixture HFO-1234yf / NH ₃ has a phenomenon of demixing and phase shift regardless of the presence of oil or not.

Claims

Composition comprising:

a heat transfer fluid comprising from 15 to 30% of ammonia and from 70 to 85% of 2,3,3,3-tetrafluoropropene; and

a lubricating oil comprising polyalkylene glycol.

The composition of claim 1, wherein the heat transfer fluid is a mixture of ammonia and 2,3,3,3-tetrafluoropropene.

The composition of claim 1 or 2, wherein the heat transfer fluid comprises 18 to 26% ammonia and 74 to 82% 2,3,3,3-tetrafluoropropene, preferably 21 to 23% d. ammonia and 77 to 79% 2,3,3,3-tetrafluoropropene.

Composition according to one of claims 1 to 3, wherein the lubricating oil is polyalkylene glycol.

Composition according to one of claims 1 to 4, wherein the lubricating oil is from 1 to 99%, preferably from 5 to 50%, more preferably from 10 to 40%, and most preferably from 15 to 35%. %, of the composition.

Composition according to one of claims 1 to 5, further comprising one or more additives chosen from heat transfer compounds, stabilizers, surfactants, tracer agents, fluorescent agents, odorants, solubilizing agents and their mixtures.

Use of polyalkylene glycol as a lubricating oil in a vapor compression circuit, in combination with a heat transfer fluid comprising 15 to 30% ammonia and 70 to 85% of 2,3,3, 3-tetrafluoropropene.

8. Use according to claim 7, wherein the polyalkylene glycol is used in a proportion of 1 to 99%, preferably 5 to 50%, more preferably 10 to 40%, and ideally 15 to 35%, relative to the sum of the polyalkylene glycol and the heat transfer fluid.

Use according to claim 7 or 8, wherein the heat transfer fluid comprises 18 to 26% ammonia and 74 to 82% 2,3,3,3-tetrafluoropropene, preferably 21 to 23%. % ammonia and 77 to 79% 2,3,3,3-tetrafluoropropene.

10. Use according to one of claims 7 to 9, wherein the heat transfer fluid consists of a mixture of ammonia and 2,3,3,3-tetrafluoropropene.

A heat transfer apparatus comprising a vapor compression circuit containing a heat transfer composition which is a composition according to one of claims 1 to 6.

12. Installation according to claim 1 1, selected from mobile installations or stationary heat pump heating, air conditioning, refrigeration, freezing and Rankine cycles.

13. Installation according to claim 1 1, which is a car air conditioning installation. A method of heating or cooling a fluid or a body by means of a vapor compression circuit containing a heat transfer fluid, said method comprising successively at least partial evaporation of the heat, compression of the heat transfer fluid, at least partial condensation of the heat transfer fluid and expansion of the heat transfer fluid, wherein the heat transfer fluid is associated with a heat transfer fluid. lubrication for forming a heat transfer composition, said heat transfer composition being a composition according to one of claims 1 to 6.

A method of reducing the environmental impact of a heat transfer facility comprising a vapor compression circuit containing an initial heat transfer fluid, said method comprising a step of replacing the initial heat transfer fluid in the heat transfer circuit. vapor compression by a final heat transfer fluid, the final heat transfer fluid having a GWP lower than the initial heat transfer fluid, wherein the final heat transfer fluid is associated with a lubricating oil to form a heat transfer composition, said heat transfer composition being a composition according to one of claims 1 to 6.

16. Use of ammonia to increase the miscibility of 2,3,3,3-tetrafluoropropene with a lubricating oil.

17. Use according to claim 16, wherein the ammonia is used in a proportion of 15 to 30%, preferably 18 to 26%, and more preferably 21 to 23%, based on the sum of 1%. ammonia and 2,3,3,3-tetrafluoropropene.

18. Use of 2,3,3,3-tetrafluoropropene to increase the miscibility of ammonia with a lubricating oil.

19. Use according to claim 18, wherein the 2,3,3,3-tetrafluoropropene is used in a proportion of 70 to 85%, preferably 74 to 82%, more preferably 77 to 79%, in relation to the sum of ammonia and 2,3,3,3-tetrafluoropropene. 20. Use according to one of claims 16 to 19, wherein the lubricating oil comprises, preferably consists of polyalkylene glycol.

21. Kit comprising:

a lubricating oil comprising a polyalkylene glycol on the other hand;

for use in a heat transfer installation comprising a vapor compression circuit.

22. Kit comprising:

- ammonia;

2,3,3,3-tetrafluoropropene;

a lubricating oil comprising a polyalkylene glycol on the other hand;

23. Kit according to claim 21 or 22, wherein the lubricating oil consists of polyalkylene glycol.

24. Kit according to one of claims 21 to 23, for use in a car air conditioning installation.