METHOD FOR COOLING AND/OR HEATING A BODY OR A FLUID IN A MOTOR VEHICLE

Abstract

A method for cooling and/or heating a body or a fluid in a motor vehicle using a system including a steam compression circuit in which flows a first heat transfer composition and a secondary circuit in which flows a second heat transfer composition. Also, an installation for cooling and/or heating a body or a fluid in a motor vehicle, a use for cooling and/or heating a body or a fluid in a motor vehicle, and a heat transfer composition including one or more heat transfer compounds having a boiling point between 0 and 40 C., chosen from among the hydrochlorofluoroolefins, the hydrofluoroolefins and combinations thereof.

Claims

1. A method for cooling a body or a fluid in a motor vehicle, by means of a system comprising a first heat transfer composition circulating in a vapor compression circuit and a second heat transfer composition circulating in a secondary circuit, the method comprising: the transfer of heat from the body or fluid to the second heat transfer composition, leading to the evaporation of this second heat transfer composition; the transfer of heat from the second heat transfer composition to the first heat transfer composition, leading to the condensation of the second heat transfer composition and the evaporation of the first heat transfer composition.

2. A method for heating a body or a fluid in a motor vehicle, by means of a system comprising a first heat transfer composition circulating in a vapor compression circuit and a second heat transfer composition circulating in a secondary circuit, the method comprising: the transfer of heat from the second heat transfer composition to the body or fluid, leading to the condensation of this second heat transfer composition; the transfer of heat from the first heat transfer composition to the second heat transfer composition, leading to the evaporation of the second heat transfer composition and the condensation of the first heat transfer composition.

3. The method as claimed in claim 1, wherein the fluid is air.

4. The method as claimed in claim 1, wherein the first heat transfer composition comprises 2,3,3,3-tetrafluoropropene.

5. The method as claimed in claim 1, wherein the second heat transfer composition comprises one or more heat transfer compounds having a boiling point of 0 to 40 C.

6. The method as claimed in claim 1, wherein the second heat transfer composition is at an essentially uniform pressure in the secondary circuit.

7. The method as claimed in claim 1, wherein the motor vehicle is an electric or hybrid vehicle.

8. An installation for cooling and/or heating a body or a fluid in a motor vehicle, comprising: a first heat transfer composition circulating in a vapor compression circuit; and a second heat transfer composition circulating in a secondary circuit; the vapor compression circuit being coupled with the secondary circuit by an intermediate heat exchanger, so as to evaporate the first heat transfer composition and to condense the second heat transfer composition, and/or to condense the first heat transfer composition and to evaporate the second heat transfer composition; and the installation comprising an additional heat exchanger configured for transferring the heat of the body or fluid to the second heat transfer composition by evaporating the second heat transfer composition, and/or configured for transferring heat of the second heat transfer composition to the body or fluid by condensing the second heat transfer composition.

9. The installation as claimed in claim 8, wherein the vapor compression circuit is reversible and further comprises means for reversing its operation.

10. The installation as claimed in claim 8, wherein the circulation of the second heat transfer composition in the secondary circuit after condensation thereof is performed by means of a pump, or by gravity, or by capillarity.

11. The installation as claimed in claim 8, wherein the secondary circuit comprises a plurality of additional heat exchangers, configured for cooling and/or heating a plurality of bodies or fluids.

12. The installation as claimed in claim 8, adapted for the air-conditioning of the passenger compartment of the vehicle, and/or the heating of the passenger compartment of the vehicle, and/or for the cooling of the battery of the vehicle, and/or the heating of the battery of the vehicle and/or the cooling of the electronic compounds of the vehicle, and/or the heating of the electronic compounds of the vehicle.

13. The installation as claimed in claim 8, wherein the first heat transfer composition comprises 2,3,3,3-tetrafluoropropene.

14. The installation as claimed in claim 8, wherein the second heat transfer composition comprises one or more heat transfer compounds having a boiling point of 0 to 40 C.

15. The method as claimed in claim 5, wherein the second heat transfer composition is chosen from hydrochlorofluoroolefins, hydrofluoroolefins, and combinations thereof.

16. The method as claimed in claim 5, wherein the second heat transfer composition is chosen from 1-chloro-3,3,3-trifluoropropene; 1-chloro-2,3,3,3-tetrafluoropropene, and 1,1,1,4,4,4-hexafluorobut-2-ene.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0052] FIG. 1 represents schematically one embodiment of an installation according to the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0053] The invention is now described in greater detail and in a nonlimiting manner in the description which follows.

[0054] The invention relates to a heat transfer method for cooling and/or heating a body or a fluid in a motor vehicle, implemented by means of a heat transfer installation. The installation contains a first and a second heat transfer composition, each heat transfer composition comprising a heat transfer fluid, which comprises one or more heat transfer compounds.

[0055] The term heat transfer compound is intended to mean a compound capable of absorbing heat by evaporating and of releasing heat by condensing, in the application under consideration.

[0056] In the context of the invention, HFO-1234yf refers to 2,3,3,3-tetrafluoropropene, HCFO-1233zd refers to 1-chloro-3,3,3-trifluoropropene, HCFO-1224yd refers to 1-chloro-2,3,3,3-tetrafluoropropene, and HFO-1336mzz refers to 1,1,1,4,4,4-hexafluorobut-2-ene.

[0057] The motor vehicle may be a combustion-powered, electric, or hybrid vehicle, preferably an electric or hybrid vehicle. It comprises at least one motor unit, which may be an electric motor or a combustion engine. When the vehicle is electric or hybrid, it comprises an electronic circuit and a traction battery, the latter denoted more simply as battery in the text below.

Installation for Cooling and/or Heating in a Vehicle

[0058] The invention relates to a method for heat transfer, comprising the cooling and/or the heating of a body or a fluid in a motor vehicle, in a heat transfer installation.

[0059] The method according to the invention may therefore be a method for cooling the body or the fluid in the vehicle.

[0060] Alternatively, the method according to the invention may be a method for heating the body or the fluid in the vehicle.

[0061] Alternatively, the method according to the invention may be a method in which one or more phases of cooling of the body or the fluid alternate with one or more phases of heating of the body or the fluid.

[0062] The method according to the invention is implemented by means of the installation set out below.

[0063] The heat transfer installation comprises a vapor compression circuit, which contains a first heat transfer composition (or refrigeration circuit), and a secondary circuit, containing a second heat transfer composition (or heat-exchange circuit).

[0064] According to one embodiment of the invention, shown schematically in FIG. 1, the vapor compression circuit 1 is coupled with the secondary circuit 2. The vapor compression circuit 1 comprises at least one first heat exchanger 3, an expansion valve 4, an intermediate heat exchanger 5, and a compressor 6. The first heat exchanger 3 is preferably an air/refrigerant exchanger which allows exchange of heat with an energy source such as the ambient air. The secondary circuit 2 comprises at least one additional heat exchanger 7.

[0065] By energy source is meant a solid and/or liquid and/or gaseous body which is able to absorb or release heat energy according to requirements. The external air, the air in the passenger compartment, the battery, and the electronic circuit of the vehicle represent examples of energy sources.

[0066] In refrigeration mode (cooling of a body or fluid in the vehicle), heat is transferred from the body or the fluid of the vehicle to the additional heat exchanger 7, leading to the evaporation of the second heat transfer composition circulating in the secondary circuit 2. The second heat transfer composition subsequently travels into the intermediate heat exchanger 5, which acts as the condenser for the secondary circuit 2. In the vapor compression circuit 1, the first heat transfer composition is compressed by the compressor 6, and passes through the first heat exchanger 3, acting as condenser (that is, it transfers heat energy to a source such as the external air), then through the expansion valve 4, in which it is expanded, and then through the intermediate heat exchanger 5, which acts as evaporator for the vapor compression circuit 1. Thus, in the intermediate heat exchanger 5, heat is transferred from the second heat transfer composition to the first heat transfer composition, leading to the condensation of the second heat transfer composition and the evaporation of the first heat transfer composition. The first heat transfer composition subsequently travels again to the compressor 6, while the second heat transfer composition travels to the additional heat exchanger 7, and enables the cooling of the body or the fluid in the vehicle.

[0067] In heat pump mode (heating of a body or fluid in the vehicle), which is not illustrated in FIG. 1, heat is transferred to the body or fluid in the vehicle from the additional heat exchanger 7, leading to the condensation of the second heat transfer composition circulating in the secondary circuit 2. The second heat transfer composition subsequently travels into the intermediate heat exchanger 5, which acts as evaporator for the secondary circuit 2. In the vapor compression circuit 1, the first heat transfer composition is expanded in the expansion valve 4, and passes through the first heat exchanger 3 acting as evaporator (that is, it absorbs heat energy from a source such as the external air), then through the compressor 6, where it is compressed, and then through the intermediate heat exchanger 5, which acts as condenser for the vapor compression circuit 1. Thus, in the intermediate heat exchanger 5, heat is transferred from the first heat transfer composition to the second heat transfer composition, leading to the condensation of the first heat transfer composition and the evaporation of the second heat transfer composition. The first heat transfer composition subsequently travels again to the expansion valve 4, while the second heat transfer composition travels to the additional heat exchanger 7, and enables the heating of the body or the fluid in the vehicle.

[0068] In some embodiments, a single heat exchanger may take on the function of the intermediate exchanger 5 or the first heat exchanger 3 described above, depending on the operating mode. Supplementary exchangers may also be added in order to take on the same functions. A system of pipes and valves may be used to provide for the change in function for each exchanger.

[0069] In some embodiments, the vapor compression circuit 1 is reversible and may further comprise means for reversing its operation.

[0070] The means for reversing the operation of the reversible vapor compression circuit 1 are means for reversing the operation of the vapor compression circuit 1 between a configuration in refrigeration mode and a configuration in heat pump mode.

[0071] The aforementioned reversal means may be means for modifying the pathway of the first heat transfer composition in the reversible vapor compression circuit 1, or means for reversing the direction of circulation of the first heat transfer composition in said circuit 1.

[0072] The abovementioned reversal means can be a four-way valve, a switchover valve, a shut-off (on/off) valve, an expansion valve, or combinations thereof.

[0073] For example, during the reversal of the operating mode of the vapor compression circuit 1, the role of a heat exchanger may be changed: for example, a heat exchanger may act as a condenser in a refrigeration mode or as an evaporator in a heat pump mode, or vice versa.

[0074] Alternatively, during the reversal of the operating mode of the vapor compression circuit 1, the role of a heat exchanger may remain the same. Since the heat exchanger is quite simply connected to other energy sources, by way of valves, it is able to absorb or release heat energy according to its function in the vapor compression circuit 1.

[0075] In some embodiments, the first heat transfer composition is able to circulate in a single direction in the vapor compression circuit 1.

[0076] In some embodiments, the first heat transfer composition is able to circulate in both directions in the vapor compression circuit 1, namely in a first direction and in an opposite direction.

[0077] The reversible vapor compression circuit 1 may typically contain pipes, tubes, hoses, a tank, or other means, in which the first heat transfer composition circulates, between the various exchangers, expansion valves, other valves, etc.

[0078] According to the operating mode of the vapor compression circuit 1refrigeration or heat pumpthe first heat exchanger 3 may act as evaporator or as energy recuperator (condenser). The same applies to the intermediate heat exchanger 5.

[0079] It is possible to use any type of heat exchanger in the vapor compression circuit 1, and especially cocurrent heat exchangers or, preferably, countercurrent heat exchangers.

[0080] According to one preferred embodiment, the invention provides for the cooling and heating methods and the corresponding installations to comprise a heat exchanger which is countercurrent with respect either to the first heat exchanger 3 or to the intermediate heat exchanger 5. The reason is that the heat-transfer compositions described in the present patent application are particularly effective with countercurrent heat exchangers. Preferably both the first heat exchanger 3 and the intermediate heat exchanger 5 are countercurrent heat exchangers.

[0081] According to the invention, the term countercurrent heat exchanger is intended to mean a heat exchanger in which heat is exchanged between a first fluid and a second fluid, the first fluid at the inlet of the exchanger exchanging heat with the second fluid at the outlet of the exchanger, and the first fluid at the outlet of the exchanger exchanging heat with the second fluid at the inlet of the exchanger.

[0082] For example, countercurrent heat exchangers include devices in which the flow of the first fluid and the flow of the second fluid are in opposite directions or virtually opposite directions. Exchangers operating in crosscurrent mode with a countercurrent tendency are also included among the countercurrent heat exchangers for the purposes of the present patent application.

[0083] The compressor 6 may be hermetic, semihermetic or open. Hermetic compressors comprise a motor part and a compression part, which are contained within an undismantlable hermetic enclosure. Semihermetic compressors comprise a motor part and a compression part, which are assembled directly with one another. The coupling between the motor part and the compression part is accessible by detaching the two parts by dismantling. Open compressors comprise a motor part and a compression part which are separate. They may operate by belt drive or by direct coupling.

[0084] The compressor used may especially be a dynamic compressor, or a positive displacement compressor.

[0085] Dynamic compressors include axial compressors and centrifugal compressors, which may have one or more stages. Centrifugal mini-compressors may also be employed.

[0086] Positive displacement compressors include rotary compressors and reciprocating compressors.

[0087] Reciprocating compressors include diaphragm compressors and piston compressors.

[0088] Rotary compressors include screw compressors, lobe compressors, scroll (or spiral) compressors, liquid ring compressors, and blade compressors. Screw compressors may preferably be twin-screw or single-screw.

[0089] In the installation which is used, the compressor 6 may be driven by an electric motor or by a gas turbine (fed, for example, by the exhaust gases of the vehicle) or by gearing.

[0090] In the installation which is used, the compressor 6 may comprise a device for injecting vapor or liquid. Injection entails introducing the refrigerant, in the liquid or vapor state, into the compressor at an intermediate level between the start and the end of compression.

[0091] The secondary circuit 2 comprises at least one additional heat exchanger 7.

[0092] Each additional heat exchanger 7 may be a fluid/solid exchanger, or fluid/fluid exchanger, or fluid/air exchanger (for heating or cooling the airfor example, the air in the passenger compartment). In these two latter cases, the additional heat exchanger or exchangers 7 may again be cocurrent heat exchangers or, preferably, countercurrent heat exchangers.

[0093] The additional heat exchangers 7 may be configured for cooling and/or heating a plurality of bodies or fluids, preferably from among air, especially the air in the passenger compartment, the battery, and electronic components of the vehicle. In order to cool or heat the battery or the electronic components, it is possible to cool or heat the air which is blown toward the battery or the electronic components; or else to place the relevant additional exchanger 7 directly in contact with the battery or the electronic components, or to integrate it in the battery or the electronic components.

[0094] In some embodiments, the secondary circuit 2 does not comprise a compressor.

[0095] In some embodiments, the second heat transfer composition is at an essentially uniform pressure in the secondary circuit, said pressure being equal to the saturation pressure of the second heat transfer composition at the temperature of the second heat transfer composition. A slight difference is possible in the event of a loss of head. The temperature of the second heat transfer composition is preferably uniform in the secondary circuit.

[0096] In some embodiments, the second heat transfer composition remains at a constant temperature during the method.

[0097] By saturation pressure is meant the pressure at which a gas phase of a composition is at equilibrium with a liquid phase at a given temperature in a closed system.

[0098] In some embodiments, the secondary circuit 2 may comprise one or more valves, especially when it comprises several additional heat exchangers 7, so as to orient the second heat transfer composition to one or more specific additional heat exchangers 7; and/or so as to allow a change in the direction of circulation of the second heat transfer composition in all or part of the secondary circuit 2.

[0099] In some embodiments, the second heat transfer composition is able to circulate in a single direction in all or part of the secondary circuit 2.

[0100] In some embodiments, the second heat transfer composition is able to circulate in both directions in all or part of the secondary circuit 2, namely in a first direction and an opposite direction.

[0101] In some embodiments, the circulation of the second heat transfer composition in the secondary circuit 2 from the intermediate heat exchanger 5 to the additional heat exchanger or exchangers 7, and/or from the additional heat exchanger or exchangers 7 to the intermediate heat exchanger 5, may be performed by means of a pump, or by gravity, or by capillarity.

[0102] In this installation according to the invention, the vapor compression circuit 1 may be coupled with the secondary circuit 2 by the intermediate heat exchanger 5. Therefore, both the first heat transfer composition and the second heat transfer composition may pass through the intermediate heat exchanger 5.

[0103] When the installation is used for cooling a body or a fluid in a vehicle, the intermediate heat exchanger 5 is able to evaporate the first heat transfer composition and condense the second heat transfer composition, and the additional heat exchanger 7 is configured for transferring the heat from the body or the fluid to the second heat transfer composition.

[0104] When the installation is used for heating a body or a fluid in a vehicle, the intermediate heat exchanger 5 is able to condense the first heat transfer composition and evaporate the second heat transfer composition, and the additional heat exchanger 7 is configured for transferring heat from the second heat transfer composition to the body or the fluid, by condensing the second heat transfer composition.

[0105] In the context of the present patent application, each evaporation and each condensation may be total or partial.

[0106] An evaporation may therefore entail transition from the liquid state to the vapor state; or from the two-phase liquid/vapor state to the vapor state; or from the liquid state to the two-phase liquid/vapor state; or from one two-phase liquid/vapor state to another two-phase liquid/vapor state.

[0107] A condensation may therefore entail transition from the vapor state to the liquid state; or from the vapor state to the two-phase liquid/vapor state; or from the two-phase liquid/vapor state to the liquid state; or from one two-phase liquid/vapor state to another two-phase liquid/vapor state.

[0108] Evaporation and condensation may take place at constant temperature, or at variable temperature in the case of nonazeotropic mixtures of heat transfer compounds.

[0109] In some embodiments, in the intermediate heat exchanger 5, one composition (the first heat transfer composition or the second heat transfer composition) is at a temperature lower than the other; preferably, the temperature difference is less than 12 C., preferably less than 8 C., and more preferably less than 5 C. In the event of the temperature of a composition not being constant in the intermediate heat exchanger 5, the reference taken for estimating the above temperature difference is the median temperature between the inlet and the outlet of the intermediate heat exchanger.

[0110] In some embodiments, the installation and the method of the invention are adapted for the air conditioning of the passenger compartment of the vehicle.

[0111] In some embodiments, the installation and the method of the invention are adapted for the heating of the passenger compartment of the vehicle.

[0112] In some embodiments, the installation and the method of the invention are adapted for the cooling of the battery of the vehicle.

[0113] In some embodiments, the installation and the method of the invention are adapted for the heating of the battery of the vehicle.

[0114] In some embodiments, the installation and the method of the invention are adapted for the cooling of the electronic components of the vehicle.

[0115] In some embodiments, the installation and the method of the invention are adapted for the heating of the electronic components of the vehicle.

[0116] In some embodiments, the installation and the method of the invention are adapted for the air conditioning of the passenger compartment of the vehicle, and/or the heating of the passenger compartment of the vehicle, and/or the cooling of the battery of the vehicle, and/or the heating of the battery of the vehicle, and/or the cooling of the electronic components of the vehicle, and/or the heating of the electronic components of the vehicle.

Heat Transfer Composition

[0117] The invention makes use of a first heat transfer composition and a second heat transfer composition, each heat transfer composition comprising a heat transfer fluid alone or in combination with lubricants and/or additives. The heat transfer fluid may comprise one or more heat transfer compounds.

[0118] The first heat transfer composition is present and circulates in the vapor compression circuit.

[0119] In some embodiments, the heat transfer fluid of the first heat transfer composition consists essentially, or consists, of HFO-1234yf.

[0120] In other embodiments, this heat transfer fluid comprises HFO-1234yf in a mixture with one or more other heat transfer compounds, such as hydrofluorocarbons and/or hydrofluoroolefins and/or hydrocarbons and/or hydrochlorofluoroolefins and/or CO.sub.2.

[0121] The hydrofluorocarbons may especially include difluoromethane (HFO-32), pentafluoroethane (HFO-125), 1,1,2,2-tetrafluoroethane (HFO-134), 1,1,1,2-tetrafluoroethane (HFO-134a), 1,1-difluoroethane (HFO-152a), fluoroethane (HFO-161), 1,1,1,2,3,3,3-heptafluoropropane (HFO-227ea), 1,1,1-trifluoropropane (HFO-263fb), and mixtures thereof.

[0122] The hydrofluoroolefins may especially include 1,3,3,3-tetrafluoropropene (HFO-1234ze), in cis and/or trans form, and preferably in trans form; and trifluoroethylene (HFO-1123).

[0123] The hydrochlorofluoroolefins may especially include 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), in Z and/or E form, and preferably in E form. In some embodiments, this heat transfer fluid comprises at least 50% of HFO-1234yf, or at least 60% of HFO-1234yf, or at least 70% of HFO-1234yf, or at least 80% of HFO-1234yf, or at least 90% of HFO-1234yf, or at least 95% of HFO-1234yf, by weight.

[0124] The additives which may be present in the first heat transfer composition of the invention may especially be selected from nanoparticles, stabilizers, surfactants, tracer agents, fluorescent agents, odorants, and solubilizers.

[0125] The total amount of additives does not exceed 5% by weight, more particularly 4%, and more particularly still 3%, and very particularly 2% by weight, or even 1% by weight, of the first heat transfer composition.

[0126] In some embodiments, the HFO-1234yf contains impurities. When they are present, they may represent less than 1%, preferably less than 0.5%, preferably less than 0. %, preferably less than 0.05% and preferably less than 0.01% (by weight) relative to the HFO-1234yf.

[0127] One or more lubricants may be present in the first heat transfer composition. These lubricants may be selected from polyol esters (POE), polyalkylene glycols (PAG), or polyvinyl ethers (PVE).

[0128] The lubricants may represent from 1 to 50%, preferably from 2 to 40%, and more preferably from 5 to 30% (by weight) of the first heat transfer composition.

[0129] The heat transfer fluid of the second heat transfer composition may comprise one or more heat transfer compounds having a boiling point of 0 to 40 C., preferably of 5 to 35 C., and more preferably of 8 to 34 C.

[0130] By boiling point of a compound is meant the temperature at which the compound boils under a pressure of 1 bar.

[0131] In some embodiments, the heat transfer fluid of the second heat transfer composition has a boiling point of 0 to 40 C., preferably of 5 to 35 C., and more preferably of 8 to 34 C.

[0132] In the case of a mixture of several compounds, the boiling point of the mixture corresponds to the average between the boiling onset temperature and the final boiling temperature at a pressure of 1 bar.

[0133] In some embodiments, with the heat transfer compound or compounds having a boiling point of 0 to 40 C., they may be selected from hydrochlorofluoroolefins, hydrofluoroolefins, and combinations thereof.

[0134] In some embodiments, the hydrochlorofluoroolefins may be selected from 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) and 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd), and combinations thereof.

[0135] The HCFO-1233zd may be in E and/or Z form.

[0136] Preferably, the HCFO-1233zd comprises more than 50 mol % of the E form, preferably more than 60 mol % of the E form, preferably more than 70 mol % of the E form, preferably more than 80 mol % of the E form, preferably more than 85 mol % of the E form, preferably more than 90 mol % of the E form, preferably more than 95 mol % of the E form, preferably more than 98 mol % of the E form, and more preferably more than 99 mol % of the E form. Preferably, it is entirely in E form.

[0137] The HCFO-1224yd may be in E and/or Z form.

[0138] Preferably, the HCFO-1224yd comprises more than 50 mol % of the Z form, preferably more than 60 mol % of the Z form, preferably more than 70 mol % of the Z form, preferably more than 80 mol % of the Z form, preferably more than 85 mol % of the Z form, preferably more than 90 mol % of the Z form, preferably more than 95 mol % of the Z form, preferably more than 98 mol % of the Z form, and more preferably more than 99 mol % of the Z form. Preferably, it is entirely in Z form.

[0139] In some embodiments, the hydrofluoroolefin may be 1,1,1,4,4,4-hexafluorobut-2-ene (HFO-1336mzz) in E and/or Z form.

[0140] The HFO-1336mzz may therefore comprise more than 50 mol % of the Z form, preferably more than 60 mol % of the Z form, preferably more than 70 mol % of the Z form, preferably more than 80 mol % of the Z form, preferably more than 85 mol % of the Z form, preferably more than 90 mol % of the Z form, preferably more than 95 mol % of the Z form, preferably more than 98 mol % of the Z form, and more preferably more than 99 mol % of the Z form. It may be entirely in Z form.

[0141] Alternatively, the HFO-1336mzz may comprise more than 50 mol % of the E form, preferably more than 60 mol % of the E form, preferably more than 70 mol % of the E form, preferably more than 80 mol % of the E form, preferably more than 85 mol % of the E form, preferably more than 90 mol % of the E form, preferably more than 95 mol % of the E form, preferably more than 98 mol % of the E form, and more preferably more than 99 mol % of the E form. It may be entirely in E form.

[0142] In some embodiments, the heat transfer compounds used in the second heat transfer composition have a latent heat of evaporation at 20 C. of more than 100 kJ/kg, preferably more than 110 kJ/kg, more preferably more than 120 kJ/kg, more preferably more than 130 kJ/kg, more preferably more than 140 kJ/kg, more preferably more than 150 kJ/kg, and more preferably more than 160 kJ/kg.

[0143] The latent heat values of the heat transfer compounds used preferentially in the second composition as heat transfer fluid are presented in the table below for a temperature of 20 C. The highest latent heat is observed for HCFO-1233zd(E).

TABLE-US-00001 Latent heat Heat transfer Temperature Pressure of evaporation composition ( C.) (bar) (kJ/kg) HCFO-1233zd(E) 20 1.07 194 HFO-1336mzz(Z) 20 0.6 171 HFO-1336mzz(E) 20 1.66 141 HCFO-1224yd(Z) 20 1.26 164

[0144] In some embodiments, the heat transfer fluid of the second heat transfer composition comprises a single heat transfer compound.

[0145] In some embodiments, the heat transfer fluid of the second heat transfer composition may be a binary mixture of heat transfer compounds.

[0146] In some embodiments, the heat transfer fluid of the second heat transfer composition may be a ternary mixture of heat transfer compounds.

[0147] The second heat transfer composition is present and circulates in the secondary circuit.

[0148] In some embodiments, the second heat transfer composition undergoes neither compression nor expansion.

[0149] In some embodiments, the second heat transfer composition comprises at least 50% of heat transfer fluid, or at least 60% of heat transfer fluid, or at least 70% of heat transfer fluid, or at least 80% of heat transfer fluid, or at least 90% of heat transfer fluid, or at least 95% of heat transfer fluid, by weight.

[0150] In some embodiments, the heat transfer fluid of the second heat transfer composition consists essentially, or consists, of heat transfer compounds.

[0151] The additives which may be present in the second heat transfer composition of the invention are the same as those described above in connection with the first heat transfer composition, and are subject to the same concentration ranges.