EP4229143A1

EP4229143A1 - Cooling a battery by immersion in a composition with a change in state

Info

Publication number: EP4229143A1
Application number: EP21798750.2A
Authority: EP
Inventors: Dominique Garrait; Laurent Abbas
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2020-10-19
Filing date: 2021-10-01
Publication date: 2023-08-23
Also published as: CN116507513A; FR3115287A1; WO2022084599A1; FR3115288A1; FR3115287B1; JP2023545560A; US20230361388A1

Abstract

The invention relates to the use of a heat transfer composition comprising from 20% to less than 100% by weight of a refrigerant comprising a compound chosen from halogenated hydrocarbons, perhalogenated compounds, fluorinated ketones, fluorinated ethers and combinations thereof, and from more than 0% to 80% by weight of a dielectric fluid, for cooling a battery, the battery comprising energy storage cells immersed in the heat transfer composition, and the heat transfer composition undergoing evaporation upon contact with the energy storage cells.

Description

Cooling of a battery by immersion in a composition with change of state

Field of invention

The present invention relates to the use of a heat transfer composition comprising at least one refrigerant fluid and at least one dielectric fluid, to cool a battery. The invention applies in particular to the batteries of electric or hybrid vehicles.

Technical background

The need to dissipate high thermal flows is essential in several applications, in particular the cooling of batteries. Liquid-vapor phase change cooling is an effective solution for dissipating large amounts of heat while maintaining battery temperature within its optimum temperature range and maintaining an even system temperature.

In particular, the batteries of electric or hybrid vehicles give maximum performance under specific conditions of use and especially in a very specific temperature range. Thus, in cold climates, the autonomy of electric or hybrid vehicles poses a problem, especially since the significant heating needs consume a large part of the stored electrical energy. In addition, at low temperatures, the available power of the battery is low, which poses a driving problem. Moreover, the cost of the battery strongly contributes to the cost of the electric or hybrid vehicle.

Conversely, battery cooling is a major safety issue. Different dielectric oils can be used to cool the battery of an electric or hybrid vehicle. However, when rapid charging of the battery is required, the use of a single-phase cooling system using, for example, dielectric oils alone is not sufficient to effectively cool the battery. In this case, it is necessary consider a cooling system with phase change of heat composition. Fluids, such as refrigerants, which are more volatile and less viscous should be used. However, these fluids have vapor pressures higher than those observed in the case of dielectric oils, which may require a reinforcement of the battery case (and therefore an increase in its weight) in order to withstand the pressure. These fluids also have a higher cost than dielectric oils. They also have a much higher density than dielectric fluids, which can weigh down the system.

In addition, it is important to use, near the battery, low or non-flammable compositions in order to eliminate any risk related to the safety of the use of these compositions.

Document FR 2973809 relates to the use of a zeolitic adsorbent to improve the thermal stability of an oil subjected to temperature variations in refrigerant fluid compositions.

Document FR 2962442 relates to a stable composition comprising 2,3,3,3-tetrafluoropropene, for use in refrigeration and air conditioning.

Document US 2014/057826 relates to a heat transfer composition comprising at least one hydrochlorofluoroolefin used for air conditioning, refrigeration and heat pump applications or used for cleaning products, components, substrates or other articles containing the substance to to clean.

WO 2019/242977 relates to a fluid-insulated switchgear which comprises a fluid compartment filled with an electrically insulating fluid and an electrical conductor placed in the fluid compartment and electrically insulated by the electrically insulating fluid.

Document WO 2019/162598 relates to the use of a refrigerant comprising 2,3,3,3-tetrafluoropropene for maintaining the temperature of a battery of an electric or hybrid vehicle in a temperature range.

Document WO 2019/162599 relates to the use of a refrigerant comprising 2,3,3,3-tetrafluoropropene for preheating a battery of an electric or hybrid vehicle from the start of the vehicle.

Document WO 2019/197783 relates to a method for cooling and/or heating a body or a fluid in a vehicle automobile, by means of a system comprising a vapor compression circuit in which circulates a first heat transfer composition and a secondary circuit in which circulates a second heat transfer composition.

Documents WO 2020/011888, WO 2020/100152, WO 2020/007954, US 9,865,907, US 10,784,545, FR 3037727, FR 3075471, FR 3085542, FR 3085545, FR 3085547, FR 69085345 describe thermal regulation systems batteries by direct contact with a fluid.

There is a need to ensure optimal operation of batteries, in particular of electric or hybrid vehicles, so as to provide high-performance batteries with long and secure lifespans without increasing costs.

Summary of the invention

The invention relates firstly to the use of a heat transfer composition comprising from 20% to less than 100% by weight of a refrigerant comprising a compound chosen from halogenated hydrocarbons, perhalogenated compounds, fluorinated ketones , fluorinated ethers and combinations thereof, and from more than 0% to 80% by weight of a dielectric fluid, for cooling a battery, the battery comprising energy storage cells immersed in the heat transfer composition, and the heat transfer composition undergoing evaporation upon contact with the energy storage cells.

In embodiments, the heat transfer composition circulates through a heat transfer circuit.

In some embodiments, the battery comprises one or more modules each comprising an enclosure in which energy storage cells are arranged, the enclosure(s) forming part of the heat transfer circuit.

In embodiments, the heat transfer circuit is thermally coupled to a secondary circuit containing an additional transfer composition.

In embodiments, the secondary circuit is the air conditioning circuit of a vehicle; and/or is a reversible heat pump circuit.

In embodiments, the refrigerant comprises or is 1 chloro 3,3,3 trifluoropropene, preferably in the E form, or is a binary, preferably azeotropic, mixture of 1 chloro 3,3,3 trifluoropropene in the Z form and 1,1,1,2,3-pentafluoropropane, or 1,1,1,1,4,4,4-hexafluorobut-2-ene in the Z form and 1,2-dichloroethylene in the E form .

In embodiments, the dielectric fluid is chosen from mineral dielectric oils, synthetic dielectric oils, and vegetable dielectric oils, and preferably from aromatic hydrocarbons chosen from alkylbenzenes, alkyldiphenylethanes, alkylnaphthalenes, methylpolyarylmethanes as well as combinations thereof, poly(alpha)olefins and polyol esters.

In embodiments, the battery is the battery of an electric or hybrid vehicle, preferably an electric or hybrid automobile.

In embodiments, the use is implemented during the charging of the battery of the vehicle, the battery of the vehicle being preferably fully charged in a period less than or equal to 30 min, and preferably less than or equal to 15 min from its total discharge.

The invention also relates to a battery assembly, in particular for an electric or hybrid vehicle, comprising one or more modules each comprising an enclosure in which are arranged energy storage cells immersed in a heat transfer composition, the transfer composition of heat comprising from 20% to less than 100% by weight of a refrigerant comprising a compound chosen from halogenated hydrocarbons, perhalogenated compounds, fluorinated ketones, fluorinated ethers as well as their combinations, and from more than 0% to 80% by weight of a dielectric fluid, the battery assembly being configured such that the heat transfer composition undergoes evaporation to cool the battery.

In some embodiments, the assembly comprises a heat transfer circuit in which the heat transfer composition circulates, the enclosure(s) of the module(s) being integrated into this heat transfer circuit.

In embodiments, the heat transfer circuit includes a pump; and/or the heat transfer circuit comprises a heat exchanger to allow heat exchange of the heat transfer composition either with the ambient air or with a heat transfer composition in a secondary circuit.

In embodiments, the dielectric fluid is chosen from mineral dielectric oils, synthetic dielectric oils, and vegetable dielectric oils, and preferably from alkylbenzenes, alkyldiphenylethanes, alkylnaphthalenes, methylpolyarylmethanes as well as their combinations, poly (alpha)olefins and polyol esters.

The invention also relates to a method of controlling the temperature of the battery of the battery assembly described above, comprising cooling the energy storage cells by the heat transfer composition by partial evaporation of the composition of heat transfer.

The present invention makes it possible to meet the need expressed above. It makes it possible to ensure optimum operation of the equipment, in particular an electric or hybrid vehicle battery (in particular the traction battery of the vehicle), so as to provide high-performance batteries with long and secure lifespans. without increasing costs.

This is accomplished through the use of a heat transfer composition comprising from 20% to less than 100% by weight of a refrigerant selected from halogenated hydrocarbons, perhalogenated compounds, fluorinated ketones, fluorinated ethers as well than combinations thereof, and from more than 0% to 80% of a dielectric fluid, the energy storage cells of the battery being immersed in the heat transfer composition and the heat transfer composition undergoing evaporation on contact energy storage cells.

Indeed, the combination of a dielectric fluid with a refrigerant makes it possible to maintain heat transfer properties far superior to those of a dielectric fluid in the liquid phase.

Compared to the use of a refrigerant alone, the invention makes it possible to reduce the cost and the weight without appreciable degradation of the performances of the battery, the lifespan, or the safety.

In addition, the vapor pressure of the composition is generally lower than that of the refrigerant alone, which makes it possible to reduce the reinforcement constraints of the installation.

Thus, the invention generally makes it possible to increase the efficiency and the lifetime of the batteries, in particular during fast charging, without increasing the costs. Preferably, the fngogene fluid has a boiling point below 50° C., even more preferably below 30° C., and in particular below 25° C. or 20° C. (at 1 bar). A relatively low boiling temperature can help slow the spread in the event of battery thermal runaway.

Preferably, the composition has a volume resistivity greater than or equal to 10 ⁶ Ω.cm at 25°C. Preferably, the composition has a breakdown voltage greater than or equal to 20 kV at 20°C. This ensures that the dielectric properties of the composition are compatible, from a safety point of view, with use in direct contact with the battery.

The refrigerant makes it possible to reduce the viscosity of the dielectric fluid and possibly to make the composition more volatile, and therefore more effective. The refrigerant also makes it possible to reduce the liquid saturation temperature of the composition (compared to a composition comprising only dielectric fluid) and to improve the efficiency of the cooling of the battery. Compared to a composition comprising only refrigerant, the invention makes it possible to reduce the constraints linked to the pressure resistance of the installation.

Advantageously, the combination of refrigerant with the dielectric fluid also makes it possible to obtain compositions which are little or not flammable.

Brief description of figures

The [Fig. 1] is a diagram which illustrates one embodiment of a battery assembly according to the invention.

The [Fig. 2] is a diagram which illustrates one embodiment of a battery assembly according to the invention.

The [Fig. 3] is a diagram which illustrates one embodiment of a battery assembly according to the invention.

The [Fig. 4] is a diagram which illustrates one embodiment of a battery assembly according to the invention.

The [Fig. 5] is a diagram which illustrates the variation of the liquid saturation temperature of the heat transfer composition at a pressure of 1 bar, as a function of the refrigerant content (see the examples part below). The temperature is represented on the ordinate (°C) and the content of dielectric fluid is represented on the abscissa (% by weight). detailed The invention is now described in more detail and without limitation in the description which follows.

Heat Transfer Composition

The heat transfer composition according to the invention comprises at least one refrigerant fluid and at least one dielectric fluid.

“Refrigerant” means a fluid capable of absorbing heat by evaporating at low temperature and low pressure and rejecting heat by condensing at high temperature and high pressure.

The refrigerant fluid comprises a compound chosen from halogenated hydrocarbons, perhalogenated compounds, fluorinated ketones, fluorinated ethers and combinations thereof.

The refrigerant can consist of one or more such compounds. Alternatively, it can also comprise one or more additional compounds chosen from hydrocarbons (alkanes or olefins, in particular propane, butane, isobutane, pentane, isopentane), CO2 and oxygenated hydrocarbons (in particular methoxymethane, ethoxyethane and methyl formate).

Preferably, the refrigerant is made up of C1, C2, C3, C4 and/or C5 compounds; more preferably C1, C2, C3 and/or C4.

Among the halogenated hydrocarbons, mention may be made of hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroolefins, hydrochloroolefins and hydrochlorofluoroolefins.

By way of example, the refrigerant can be chosen from 1,1,1,4,4,4-hexafluorobut-2-ene (HFO-1336mzz, E or Z isomer), 1-chloro-3,3 ,3-trifluoropropene (HCFO-1233zd, E or Z isomer), 3,3,4,4,4-pentafluorobut-1-ene (HFO-1345fz), 2,4,4,4-tetrafluorobut-1- ene (HFO-1354mfy), 1,1,2-trifluoroethylene (HFO-1123), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,3,3,3-tetrafluoropropene (HFO- 1234ze, E or Z isomer, preferably E), 1 -chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd, E or Z isomer, preferably Z), difluoromethane (HFC-32), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1-difluoroethane (HFC-152a), pentafluoroethane (HFC-125) , 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,2,3-pentafluoropropane (HFC-245eb), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), 1,1,1,3,3-pentafluorobutane (HFC-365mfc), fluoroethane (HFC-161), 1,1,1,2,3,3,3-heptafluoropro pane (HFC-227ea), 1,1,1-trifluoropropane (HFC-263fb), 1,2-dichloroethylene (HCO-1130, E or Z isomer, preferably E) and combinations thereof.

Preferred compounds include HCFO-1233zd (preferably in E-form), HFO-1336mzz (preferably in Z-form) and HCFO-1224yd (preferably in Z-form).

Perhalogen compounds are composed of carbon atoms and halogen atoms only. Mention may be made, for example, of perfluorinated compounds such as dodecafluoropentane, tetradecafluorohexane, hexadecafluoroheptane and their combinations.

Among the fluorinated ketones, mention may be made, for example, of fluorinated mono ketones, perfluorinated monoketones such as 1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone and their combinations.

Among the fluorinated ethers, mention may be made, for example, of hydrofluoroethers such as methoxynonafluorobutane (HFE7100), ethoxy-nonafluorobutane (HFE-7200), 1-methoxyheptafluoropropane (HFE-7000), perfluoropolyethers and combinations thereof.

The refrigerant can comprise several, for example two, or three, or four or five compounds as described above.

For example, the refrigerant may consist (or consist essentially) of:

- a mixture of HFO-1234yf and HFC-134a;

- a mixture of HFO-1336mzz(Z) and HCO-1130(E);

- a mixture of HFO-1234ze(E) and HFC-227ea;

- a mixture of HFO-1234yf, HFC-134a and HFC-152a;

- a mixture of HFC-32, HFC-152a and HFO-1234ze(E);

- a mixture of CO2, HFC-134a and HFO-1234ze(E);

- a mixture of HFC-32, HFO-1234ze(E) and butane;

- a mixture of HFC-32, HFC-125 and HFO-1234ze(E);

- a mixture of HFC-32, HFC-125, HFO-1234yf, HFC-134a and HFO-1234ze(E);

- a mixture of HFC-32, HFC-125, HFO-1234yf and HFC-134a;

- a mixture of HFC-134a and HFO-1234ze(E);

- a mixture of HFC-32, HFC-125 and HFO-1234yf;

- a mixture of HFC-32 and HFO-1234yf;

- a mixture of CO2, HFC-32 and HFO-1234yf);

- a mixture of HFC-32, HFC-134a and HFO-1234ze(E);

- a mixture of HFC-32, HFO-1234yf and HFC-152a;

- a mixture of HFC-32, HFO-1234yf and HFO-1234ze(E); - a mixture of HFC-32, HFC-125, HFC-134a and HFO-1234ze(E);

- a mixture of HFC-32, HFC-125, HFC-134a and HFO-1234ze(E);

- a mixture of CO2, HFC-32, HFC-125, HFO-1234yf and HFC-134a;

- a mixture of HFC-32, HFC-125, HFO-1234ze(E) and HFC-227ea; and

- a mixture of HFC-32, propane and HFO-1234yf.

Thus, the refrigerant can be a pure substance or a mixture. When it is a mixture, it is preferably an azeotropic or quasi-azeotropic mixture.

Preferred azeotropic compositions are the refrigerants:

- R-513A (56% HFO-1234yf and 44% HFC-134a);

- R-513B (58.5% HFO-1234yf and 41.5% HFC-134a);

- R-514A (74.7% HFO-1336mzz(Z) and 25.3% HCO-1130(E));

- R-515A (88% HFO-1234ze(E) and 12% HFC-227ea);

- R-516A (77.5% HFO-1234yf, 8.5% HFC-134a and 14% HFC-152a).

Alternatively, in certain embodiments, zeotropic compositions can be used, and in particular refrigerants:

_ R-444A (12% HFC-32, 5% HFC-152a and 83% HFO-1234ze(E));

_ R-444B (41.5% HFC-32, 10% HFC-152a and 48.5% HFO-1234ze(E));

- R-445A (6% CO2, 9% HFC-134a and 85% HFO-1234ze(E));

- R-446A (68% HFC-32, 29% HFO-1234ze(E) and 3% butane);

_ R-447A (68% HFC-32, 3.5% HFC-125 and 28.5% HFO-1234ze(E));

- R-447B (68% HFC-32, 8% HFC-125 and 24% HFO-1234ze(E));

- R-448A (26% HFC-32, 26% HFC-125, 20% HFO-1234yf, 21% HFC-134a and 7% HFO-1234ze(E));

- R-449A (24.3% HFC-32, 24.7% HFC-125, 25.3% HFO-1234yf and 25.7% HFC-134a);

- R-449B (25.2% HFC-32, 24.3% HFC-125, 23.2% HFO-1234yf and 27.3% HFC-134a);

- R-449C (20% HFC-32, 20% HFC-125, 31% HFO-1234yf and 29% HFC-134a); - R-450A (42% HFC-134a and 58% HFO-1234ze(E));

- R-451A (89.8% HFO-1234yf and 10.2% HFC-134a);

- R-451 B (88.8% HFO-1234yf and 11.2% HFC-134a);

- R-452A (11% HFC-32, 59% HFC-125 and 30% HFO-1234yf);

- R-452B (67% HFC-32, 7% HFC-125 and 26% HFO-1234yf);

- R-452C (12.5% HFC-32, 61% HFC-125 and 26.5% HFO-1234yf);

- R-454A (35% HFC-32 and 65% HFO-1234yf);

- R-454B (68.9% HFC-32 and 31.1% HFO-1234yf);

- R-454C (21.5% HFC-32 and 78.5% HFO-1234yf);

- R-455A (3% CO2, 21.5% HFC-32 and 75.5% HFO-1234yf);

- R-456A (6% HFC-32, 45% HFC-134a and 49% HFO-1234ze(E));

- R-457A (18% HFC-32, 70% HFO-1234yf and 12% HFC-152a);

- R-459A (68% HFC-32, 26% HFO-1234yf and 6% HFO-1234ze(E));

- R-459B (21% HFC-32, 69% HFO-1234yf and 10% HFO-1234ze(E));

- R-460A (12% HFC-32, 52% HFC-125, 14% HFC-134a and 22% HFO-1234ze(E));

- R-460B (28% HFC-32, 25% HFC-125, 20% HFC-134a and 27% HFO-1234ze(E));

- R-460C (2.5% HFC-32, 2.5% HFC-125, 46% HFC-134a and 49% HFO-1234ze(E));

- R-460A (12% HFC-32, 52% HFC-125, 14% HFC-134a and 22% HFO-1234ze(E));

- R-463A (6% CO2, 36% HFC-32, 30% HFC-125, 14% HFO-1234yf and 14% HFC-134a);

- R-464A (27% HFC-32, 27% HFC-125, 40% HFO-1234ze(E) and 6% HFC-227ea); and

- R-465A (21% HFC-32, 7.9% propane and 71.1% HFO-1234yf).

All percentages given are by weight. In certain preferred embodiments, the fngongene fluid comprises HCFO-1233zd in E or Z form, and more preferably in E form.

Preferably, the heat transfer composition according to the invention essentially comprises a single compound, as refrigerant. In this case, it is preferable that this refrigerant is HCFO-1233zd in E or Z form, and even more preferably in E form.

Impurities may be present up to, for example, 1% by weight at the most.

The refrigerant may in particular comprise, by weight:

- at least 99.5% of HCFO-1233zd(E), preferably at least 99.7%, more preferably at least 99.8%;

- an HFC-245fa content of less than or equal to 500 ppm, preferably from 1 to 500 ppm, more preferably from 2 to 300 ppm;

- a content of HFO-1234ze (E or Z) less than or equal to 100 ppm, preferably from 1 to 100 ppm, more preferably from 2 to 50 ppm;

- a content of HCFO-1233zd (Z) less than or equal to 100 ppm, preferably from 1 to 100 ppm, more preferably from 2 to 50 ppm.

Other favorite compositions are:

- a mixture consisting (or consisting essentially) of HCFO-1233zd(E) and HFC-245eb, preferably a quasi-azeotropic or azeotropic composition;

- a mixture consisting (or consisting essentially) of HFO-1366mzz(Z) and HCO-1130(E), preferably a quasi-azeotropic or azeotropic composition, and more preferably the refrigerant R-514A.

The refrigerant according to the invention may in particular have a liquid viscosity of 0.1 to 2 cP at 20° C., preferably of 0.2 to 0.9 CP at 20° C. The viscosity can be measured according to the method indicated in example 2 below.

The refrigerant according to the invention may in particular have a liquid saturation temperature of 0 to 50° C., preferably of 10 to 30, in particular of 15 to 25° C., at 1 bar.

The refrigerant according to the invention may in particular have a density of 1 to 1.7, preferably of 1 to 1.5, preferably 1 to 1.4 at 20°C.

The refrigerant according to the invention may in particular have a liquid saturation pressure of less than or equal to 2 bar at 30°C. By "dielectric fluid" is meant, within the meaning of the present invention, a fluid, generally an oil, which does not (or only slightly) conduct electricity but allows electrostatic forces to be exerted.

By “oil” is meant a fatty substance which is in the liquid state at ambient temperature and which is immiscible with water. Oils are fatty liquids, of vegetable, mineral or synthetic origin. It can be chosen from oils belonging to groups I to V as defined in the API classification (or their equivalents according to the ATIEL classification).

Insulating (dielectric) oils have the characteristics of heat transfer fluids and therefore participate in heat transfer just like the refrigerant.

The oil included in the heat transfer composition can be chosen in particular from mineral dielectric oils, synthetic dielectric oils which may be biosourced, and vegetable dielectric oils as well as combinations thereof.

Preferably, the dielectric fluid comprises at least one mineral dielectric oil. Non-limiting examples of such mineral dielectric oils include paraffinic oils and naphthenic oils, such as dielectric oils of the Nytro family, marketed by the company Nynas (in particular Nytro Taurus, Nytro Libra, Nytro 4000X and Nytro 10XN), and Dalia, marketed by Shell.

The mineral dielectric oils can preferably be paraffinic oils (that is to say saturated linear or branched hydrocarbons) such as Nytro Taurus oil marketed by Nynas and Dalia oil marketed by Shell, or naphthenics (that is to say cyclic paraffins) such as Nytro libra and Nytro 10XN oils marketed by the company Nynas, aromatic compounds (that is to say cyclic unsaturated hydrocarbons containing one or more cycles characterized by double bonds alternating with single bonds) and non-hydrocarbon compounds.

Preferably, the dielectric fluid is an optionally biosourced synthetic dielectric oil. Preferably, they may be aromatic hydrocarbons, aliphatic hydrocarbons, silicone oils, esters and polyesters, in particular polyol esters, as well as mixtures of two or more of them in all proportions.

Among the aromatic hydrocarbons, mention may be made, in a non-limiting manner, of alkylbenzenes, alkyldiphenylethanes (for example phenyloxyxlyethane (PXE), phenylethylphenylethane (PEPE), mono-isopropylbiphenyl (MIPB), 1,1-diphenylethane (1,1-DPE)), alkylnaphthalenes (for example di-iso-propylnaphthalene (DIPN)), methylpolyarylmethanes (for example benzyltoluene (BT) and dibenzyltolulene DBT), and their mixtures. In said aromatic hydrocarbons, it should be understood that at least one ring is aromatic and that optionally one or more other ring(s) present may be partially or totally unsaturated. Mention may in particular be made of the dielectric fluids marketed by Soltex Inc, by the company Arkema under the name of Jarylec®, and SAS 60E from the company JX Nippon Chemical Texas Inc.

Among the aliphatic hydrocarbons, mention may be made, without limitation, of alkanes, poly(apha)olefins (PAO), for example polyisobutenes (PIB) or olefins of the vinylidene type, such as those marketed for example by the company Soltex Inc.

The alkanes can in particular comprise at least 8 carbon atoms, for example between 8 and 22 carbon atoms, preferably between 15 and 22 carbon atoms.

The PAOs can be chosen from group IV and are for example obtained from monomers comprising from 4 to 32 carbon atoms, for example from octene or decene. The weight average molecular weight of PAO can vary quite widely. Preferably, the weight-average molecular mass of the PAO is less than 600 Da. The weight-average molecular mass of the PAO can also range from 100 to 600 Da, from 150 to 600 Da, or even from 200 to 600 Da. For example, PAOs having a kinematic viscosity, measured at 100°C according to the ASTM D445 standard, ranging from 1.5 to 8 mm ² /s are sold commercially by Ineos under the brands Durasyn® 162, Durasyn® 164, Durasyn® 166 and Durasyn® 168.

Among the silicone oils, mention may be made, without limitation, of the linear silicone oils of the polydimethylsiloxane type, such as for example those marketed by the company Wacker under the name Wacker® AK.

Among the synthetic esters, mention may be made, without limitation, of esters of the phthalic type such as dioctylphthalate (DOP) or di-isononylphthalate (DINP) (marketed for example by the company BASF).

Mention may also be made, in a non-limiting manner, of the esters resulting from the reaction between a polyalcohol and an organic acid, in particular an acid chosen from saturated or unsaturated C4 to C22 organic acids. By way of nonlimiting examples of such organic acids, mention may be made of undecanoic acid, heptanoic acid, octanoic acid, palmitic acid, and their mixtures. Among the polyols which can be used for the synthesis of the aforementioned esters, mention may be made, by way of non-limiting examples, of pentaerythritol for the synthesis of the oil MIVOLT DF7 Midel 7131, and Mivolt DFK from the company M&I Materials.

The esters can for example be diesters of formula R ^a -C(O)-O-([C(R)2]nO) _s -C(O)-R ^b , in which each R independently represents an atom of hydrogen or a C1-C5 alkyl group, linear or branched, in particular a methyl, ethyl or propyl group, in particular methyl; s is 1, 2, 3, 4, 5 or 6; n is 1, 2 or 3; it being understood that, when s is different from 1, the n can be identical or different; and R ^a and R ^b , which are identical or different, independently represent hydrocarbon groups, saturated or unsaturated, linear or branched, having a linear sequence of 6 to 18 carbon atoms. Preferably, when s and n are identical and are equal to 2, at least one of the groups R represents a C1-C5 alkyl group, linear or branched; and when s is 1 and n is 3, at least one of the R groups linked to the carbon in the beta position of the oxygen atoms of the ester functions represents a hydrogen atom.

The synthetic esters resulting from the reaction between a polyalcohol and an organic acid are for example Midel 7131 from the company M&l Materials or else the esters of the Nycodiel range from the company Nyco.

Among the natural esters and vegetable oils, mention may be made, without limitation, of products derived from oily seeds or other sources of natural origin. Mention may be made, by way of example and in a non-limiting manner, of FR3™ or even Envirotemp™ marketed by the company Cargill or even Midel eN 1215 marketed by the company M&I Materials.

It is also possible to use a polyalkylene glycol (PAG), in particular obtained by polymerization or copolymerization of alkylene oxides comprising from 2 to 8 carbon atoms, in particular from 2 to 4 carbon atoms.

The heat transfer composition according to the invention may comprise one oil or several, for example two, or three, or four or five oils.

A preferred dielectric fluid is a polyol ester made from pentaerythritol.

Another preferred dielectric fluid is a poly(apha)olefin (PAO) comprising mainly (that is to say more than 50% by weight) isoparaffins comprising from 4 to 32 carbon atoms. This fluid belongs to group IV of the API classification.

Preferably, the heat transfer composition according to the invention comprises a single dielectric fluid.

The dielectric fluid may in particular have a viscosity of 1 to 60 cP at 20° C. according to the ISO3104 standard.

The dielectric fluid may in particular have a boiling temperature above 30° C., as measured by ebulliometry.

The dielectric fluid may be present in the composition at a content of more than 0% to 80%, preferably more than 0 to 65%, more preferably 10 to 45% by weight relative to the total weight of the transfer composition heat.

For example, this content may be more than 0 to 5%; or 5 to 10%; or 10 to 15%; or 15 to 20%; or 20 to 25%; or 25 to 30%; or 30 to 35%; or 35 to 40%; or 40 to 45%; or 45 to 50%; or 50 to 55%; or 55 to 60%; or 60 to 65%; or 65 to 70%; or 70 to 75%; or 75 to 80%, by weight based on the total weight of the heat transfer composition.

The refrigerant may be present in the composition at a content of 20 to less than 100%, preferably 35 to less than 100%, more preferably 55 to 90% by weight relative to the total weight of the transfer composition heat.

For example, this content may be from 20 to 25%; or 25 to 30%; or 30 to 35%; or 35 to 40%; 40 to 45%; or 45 to 50%; or 50 to 55%; or 55 to 60%; or 60 to 65%; or 65 to 70%; or 70 to 75%; or 75 to 80%; or 80 to 85%; or 85 to 90%; or 90 to 95%; or from 95 to less than 100%, by weight based on the total weight of the heat transfer composition.

In certain embodiments, the heat transfer composition according to the invention comprises a polyol ester made from pentaerythritol and at least one fluorinated or fluorochlorinated hydrocarbon, such as for example, without limitation, a hydrofluoropropane, a hydrofluoropropene, a hydrochlorofluoropropane, a hydrochlorofluoropropene, as well as mixtures thereof in all proportions.

In other embodiments, the heat transfer composition according to the invention comprises a poly(alpha)olefin (PAO) and at least one fluorinated or fluorochlorinated hydrocarbon, such as for example, without limitation, a hydrofluoropropane, a hydrofluoropropene, a hydrochlorofluoropropane, a hydrochlorofluoropropene, as well as mixtures thereof in all proportions.

Preferably, the heat transfer composition according to the invention comprises HCFO-1233zd (preferably in the E form) and a polyol ester made from pentaerythritol. Even more preferably, the heat transfer composition according to the invention consists essentially, or even consists, of HCFO-1233zd (preferably in the E form) and a polyol ester made from pentaerythritol.

Preferably, the heat transfer composition according to the invention comprises HCFO-1233zd (preferably in the E form) and a poly(apha)olefin (PAO). Even more preferentially, the heat transfer composition according to the invention essentially consists, or even consists, of HCFO-1233zd (preferably in the E form) and a poly(alpha)olefin (PAO). It may also consist essentially, or consist, of HCFO-1233zd in Z-form, HFC-245eb and PAO. It may also consist essentially, or consist, of HFO-1336mzz in Z-form and PAO. It may also consist essentially, or consist, of HFO-1336mzz in Z-form, HCO-1130 in E-form and PAO.

The composition which can be used in the context of the present invention may also comprise one or more additives and/or fillers, for example chosen from, without limitation, antioxidants, passivators, pour point depressants, inhibitors of decomposition, perfumes and flavorings, colorants, preservatives, and mixtures thereof. The presence of a decomposition inhibitor is particularly preferred.

Among the antioxidants which can be advantageously used in the composition, mention may be made, by way of non-limiting examples, of phenolic antioxidants, such as for example dibutylhydroxytoluene, butylhydroxyanisole, tocopherols, as well as the acetates of these phenolic antioxidants; antioxidants of the amine type, such as for example phenyl-a-naphthylamine, of the diamine type, for example N,N'-di-(2-naphthyl)-para-phenylenediamine, ascorbic acid and its salts, ascorbic acid esters, alone or in mixtures of two or more of them or with other components, such as for example green tea extracts, coffee extracts.

A particularly suitable antioxidant is that commercially available from Brenntag under the trade name lonol®. The passivators that can be used in the context of the present invention are advantageously chosen from triazole derivatives, benzimidazoles, imidazoles, thiazole, benzothiazole. By way of example and without limitation, dioctylaminomethyl-2,3-benzotriazole and 2-dodecyldithioimidazole can be mentioned.

Among the pour point depressants which may be present, mention may be made, by way of non-limiting examples, of fatty acid esters of sucrose, acrylic polymers such as poly(alkyl methacrylate) or alternatively poly(alkyl acrylate).

The preferred acrylic polymers are those whose molecular weight is between 50,000 g. mol ^-1 and 500000 g. mol ^-1 . Examples of these acrylic polymers include polymers which may contain linear alkyl groups comprising 1 to 20 carbon atoms.

Among these, and still by way of non-limiting examples, mention may be made of poly(methyl acrylate), poly(methyl methacrylate), poly(heptyl acrylate), poly(heptyl methacrylate ), poly(nonyl acrylate), poly(nonyl methacrylate), poly(undecyl acrylate), poly(undecyl methacrylate), poly(tridecyl acrylate), poly(tridecyl methacrylate), poly(pentadecyl acrylate), poly(pentadecyl methacrylate), poly(heptadecyl acrylate), and poly(heptadecyl methacrylate).

An example of such a pour point depressant is commercially available from Sanyo Chemical Industries, Ltd, under the tradename Aclube.

According to a very particularly preferred aspect, a decomposition inhibitor is present as an additive. The decomposition inhibitor can in particular be chosen from carbodi-imide derivatives such as diphenyl carbodi-imide, di-tolylcarbodi-imide, bis(isopropylphenyl)-carbodi-imide, bis(butylphenyl)carbodi-imide; but also from phenylglycidyl ethers, or esters, alkylglycidyl ethers, or esters, 3,4-epoxycyclohexylmethyl-(3,4-epoxycyclohexane) carboxylate, compounds of the anthraquinone family, such as for example 0-methylanthraquinone marketed under the name "BMAQ", epoxy derivatives such as vinylcyclohexene diepoxides, 3,4-epoxy-6-methylcyclohexylmethyl-(3,4-epoxy-6-methylhexane) carboxylate, epoxy resins of the phenol novolak type, diglycidyl epoxy ether of bisphenol A, such as DGEBA or CEL 2021 P, available in particular from the company Whyte Chemicals. The total amount of additives preferably does not exceed 5% by weight, in particular 4%, more particularly 3% and very particularly 2% by weight or even 1% by weight of the heat transfer composition.

The composition according to the invention can be prepared by any means well known to those skilled in the art, for example by simply mixing the various components of the composition according to the invention.

In some embodiments, the heat transfer composition contains impurities. When they are present, they can represent less than 1%, preferably less than 0.5%, preferably less than 0.1%, preferably less than 0.05% and preferably less than 0.01% ( by weight) relative to the heat transfer composition.

The choice of the various components is not limiting provided that the heat transfer composition according to the invention has the properties (thermal conductivity, viscosity, resistivity, breakdown voltage, etc.) required for the intended application. Preferably a volume resistivity greater than or equal to 10 ⁶ Ω.cm at 25° C., and preferably greater than or equal to 10 ⁷ Ω.cm or 10 ⁸ Ω.cm. The resistivity of a material represents its ability to oppose the flow of electric current. In other words, volume resistivity is an indication of the dielectric properties of the composition. The volume resistivity is measured according to the IEC 60247 standard.

For example, this volume resistivity can be from 10 ⁶ to 5×10 ⁶ Q.cm; or from 5x10 ⁶ to 10 ⁷ Q.cm; or from 10 ⁷ to 5x10 ⁷ Q.cm; or from 5x10 ⁷ to 10 ⁸ Q.cm; or from 10 ⁸ to 5x10 ⁸ Q.cm; or from 5x10 ⁸ to 10 ⁹ Q.cm; or more than 10 ⁹ Q.cm.

In addition, the heat transfer composition according to the invention preferably has a breakdown voltage at 20° C. greater than or equal to 20 kV, preferably greater than or equal to 20 kV, preferably greater than or equal to 30 kV, of preferably greater than or equal to 50 kV, and more preferably greater than or equal to 100 kV. By “breakdown voltage” is meant the minimum electric voltage which renders a portion of an insulator conductive. Thus, this parameter is also an indication of the dielectric properties of the composition. The breakdown voltage is measured according to the IEC 60156 standard.

For example, the breakdown voltage at 20° C. of the composition according to the invention can be from 25 to 30 kV; or 30 to 40 kV; or 40 to 50 kV; or 50 to 60 kV; or 60 to 70 kV; or 70 to 80 kV; or 80 to 90 kV; or 90 to 100 kV; or 100 to 110 kV; or 110 to 120 kV; or 120 to 130 kV; or 130 to 140 kV; or 140 to 150 kV. The heat transfer composition according to the invention can also have a liquid saturation temperature of 20 to 80° C., and preferably of 30 to 70° C. at a pressure of 1 bar. For example, this temperature can be from 20 to 25° C.; or 25 to 30°C; or 30 to 35°C; or 35 to 40°C; or 40 to 45°C; or 45 to 50°C; or 50 to 55°C; or 55 to 60°C; or 60 to 65°C; or 65 to 70°C; or 70 to 75°C; or 75 to 80°C.

The heat transfer composition according to the invention may in particular have a viscosity of 0.1 to 20 cP at 20° C. according to the ISO 3104 standard.

The heat transfer composition according to the invention is preferably not very flammable (that is to say having a high flash point, for example greater than 150° C., or 200° C., or 250° C., or at 300°C, according to the ISO 3679 and ISO 3680 standards) or preferably non-flammable.

Use of the heat transfer composition

Referring to Figure 1, the battery 402 can power at least one motor 404, including a vehicle engine. The vehicle is preferably an automobile, or possibly a construction machine, scooter, motorcycle, truck, ship, aircraft, etc.

The battery can comprise a set of energy storage cells (or accumulators), which can be grouped into a single or several modules. Each module can contain a plurality of cells arranged in a hermetic enclosure. Each module enclosure can be configured to hold the cells in a fixed fashion.

The battery may comprise identical or different modules. The modules can be assembled together mechanically and/or electrically connected, to form the battery. The modules can be electrically connected in series, or in parallel.

Each enclosure may for example comprise an upper portion and a lower portion connected together, for example by welding, gluing or screwing.

The cells can for example be cylindrical in shape. Each module can comprise from 2 to 200 cells, preferably from 4 to 100 cells, more preferably from 6 to 50 cells. The cells can for example be arranged in N rows of M cells in each module. N can be for example 1 to 10, for example can be 2. M can be for example 1 to 60, and for example can be a multiple of 3 (i.e. 3, 6, 12, 18, 30... ). In some embodiments, the cells may be arranged in a three-dimensional arrangement within each module, with a stacking of P layers of NxM cells. The number of layers P can then be for example from 2 to 5. Alternatively, a single layer is present.

The cells can be, for example, nickel-cadmium (NiCd), nickel metal hydride (Ni-M-H) or lithium-ion (Li-ion) rechargeable cells.

Each enclosure can for example be made of plastic material, in particular polystyrene, polyvinyl chloride, polycarbonate, polyethylene, polypropylene, acrylic polymer and in particular polymethyl methacrylate, phenolic resin, etc. Alternatively, it can be made of metallic material, for example in aluminium.

The heat transfer composition is used to cool a battery. This cooling is accomplished by placing the heat transfer composition in direct contact with energy storage cells of the battery, the heat transfer composition at least partially changing state (undergoing evaporation) upon contact with the cells. In other words, the energy storage cells are immersed in the heat transfer composition.

By "immersed" is meant that the cells are in contact with the heat transfer composition. More particularly, the exterior surfaces of the cells are in contact with the heat transfer composition. Preferably, they are in contact with the heat transfer composition essentially in liquid form.

The cells can thus be placed in a bath of heat transfer composition. The heat transfer composition can occupy the entire internal space of the module, between the cells and the wall of the enclosure, or preferably a gaseous sky can be provided. Preferably, the entire surface of the cells in the enclosure is in contact with the composition in liquid form.

Alternatively, the surface of the cells can be covered with a liquid film obtained using suitable means (watering, projection, jet, etc.) and/or by specific treatment of the surface of the cells.

For example, the heat transfer composition can be sprayed onto the cells through one-way or multi-way nozzles. They can for example be arranged between the cells so as to project the heat transfer composition onto the side faces of the cells. Alternatively, they are placed above the cells to project the heat transfer composition onto the top faces of the cells. The composition can be projected in the form of a jet, or stream, or be in the form of a mist. The composition can be recovered in a tank and recirculated using a pump. A heat exchanger and/or a heating means (for example resistor) can be arranged in the reservoir, or upstream or downstream of the pump, to make it possible to supply or remove heat from the composition. In this variant, the bringing into contact of the liquid composition with the surface of the cells can be carried out only when there is a need to regulate the temperature of the battery. The rest of the time, and in particular when the battery is not in operation, the surface of the cells may not be in contact with the heat transfer composition.

Optionally, the surface of the cells can be coated with a hydrophilic film to allow a layer of liquid heat transfer composition to be distributed over the surface of the cells. For example, a nanostructured SiO2 film can be employed. Alternatively, a filamentary or fibrous structure (comprising one or more rovings, or a woven or nonwoven textile), or even an agglomerated metal powder, can be placed on the surface of the cells, to make it possible to distribute a layer of liquid of composition heat transfer on the cell surface by capillarity.

The heat transfer composition is totally or partially vaporized in contact with the cells (in order to cool them).

Preferably, the change of state is partial: the dielectric fluid essentially remains in the liquid state, while the refrigerant undergoes a total or partial change of state.

This makes it possible to take full advantage of the thermal properties of the heat transfer composition. Indeed, the cooling by direct contact of the cells of the battery with the heat transfer composition is useful in the event of rapid charging of the battery, which involves the rapid heating of the latter. It allows the temperature to be maintained evenly in its optimal operating range.

The heat transfer composition is contained in a device, adapted to allow the composition to exchange heat with the cells of the battery, and preferably also with a secondary source.

This device, together with the battery itself, constitutes a battery assembly according to the invention.

The secondary source may be ambient air, or an additional heat transfer composition. When it comes to ambient air, one or more fans can be used to increase the heat exchanged with it.

The heat transfer composition can be static or circulating.

If it is static, the device comprises the enclosure or enclosures containing the cells of the battery, as well as the heat transfer composition in contact with these cells. The heat transfer composition exchanges heat with the environment or an additional heat transfer composition via the enclosure itself. The internal wall and/or the external wall of the enclosure may thus comprise heat dissipation elements such as fins or another structure in relief to facilitate heat exchanges with the environment or the additional heat transfer composition. Preferably, the heat transfer composition can exchange heat with the additional heat transfer composition, via a heat exchanger located in the enclosure, or directly via the wall of the enclosure, or via plates or channels on the wall of the enclosure.

For example, a condenser can be arranged in an upper wall of the enclosure. Thus, the heat transfer composition which undergoes evaporation while cooling the cells can be condensed in this condenser, to return in liquid form. This condenser allows heat exchange with the ambient air or with an additional heat transfer composition. The condenser may include channels formed in the upper wall of the enclosure. Ridges, spikes or other reliefs can help the condensed heat transfer composition to trickle down to the bottom of the enclosure.

The pressure in the enclosure can vary depending on the temperature in the enclosure. The pressure in the enclosure can for example remain below 5 bar, or below 4 bar, or below 2 bar.

When the heat transfer composition is circulating, the device includes a main heat transfer circuit, as shown in Figure 1.

The flow rate of the heat transfer composition in the main circuit can be 0 to 100 L/min, preferably 5 to 50 L/min.

The enclosure of each module may be provided with at least one fluid inlet and at least one fluid outlet, to allow the heat transfer composition to pass through the enclosure, the cells being immersed, preferably entirely, in the heat transfer composition. To avoid thermal shocks, it may be preferred for the temperature of the heat transfer composition, at the inlet of the enclosure, to be greater than or equal to 10° C., for example between approximately 20 and approximately 30° C.

To ensure better homogeneity of the thermal regulation of the battery, it may be preferred that the temperature glide (difference between the temperature of the heat transfer composition at the outlet of the enclosure and the temperature of the heat transfer composition at the entry of the enclosure) or, in absolute value, less than or equal to 10°C, preferably 5°C, more preferably 2°C, more preferably 1°C.

The modules may be fluidly connected in series, or in parallel, with respect to the circulation of the heat transfer composition.

Referring again to Figure 1, the main heat transfer circuit can be configured to transport the heat transfer composition from at least one heat exchanger 408, 408' to the battery 402, and back again. from the battery 402 to the at least one heat exchanger 408, 408'. The module enclosure(s) are integrated into this main circuit. The circulation in the main circuit can be done by convection. The main circuit may also include one or more lines for supplying the heat transfer composition to the battery and for collecting it; and possibly to transport it between modules of the battery. Alternatively, the enclosures of the modules can be in direct contact so as to allow the assembly of the respective fluid inlets and outlets of the modules. In this case, seals can be provided between the assembled inlets and outlets.

Distributors and collectors can be attached to or integrated into the enclosures, when several inlets and/or several fluid outlets are provided in each enclosure. In certain embodiments, portions of distributors and collectors can be formed in the enclosures themselves, so as to allow the collection and distribution of the heat transfer composition from one module to another when the respective enclosures are assembled.

When the heat transfer composition is used to cool the battery, it is completely or preferably partially vaporized as it passes through the enclosure(s).

Preferably, the change of state is made between a completely liquid composition and a two-phase liquid-vapor composition when passing through the battery, then again towards a completely liquid (within I heat exchanger 408, 408) before returning to the battery.

The transport of the heat transfer composition in the main circuit can be ensured by one or more pumps 406. Preferably, the main circuit does not include a compressor: in other words, the heat transfer circuit is not a circuit vapor compression.

The heat exchanger 408 may in particular be a radiator ensuring a heat exchange with the ambient air.

Alternatively, the heat exchanger 408′ couples the main circuit with a secondary circuit in which circulates an additional heat transfer composition, which itself exchanges heat with another source, for example with the ambient air.

The additional heat transfer composition can be the same as or different from the heat transfer composition. For example, it can be a refrigerant as described above, not mixed with a dielectric fluid. For example, the composition may comprise HFO-1234yf, combined where appropriate with one or more lubricants and other additives. Alternatively, it can be a mixture of water and glycol for example.

This secondary circuit can be a refrigeration circuit, comprising a compressor, an expander, an evaporator and a condenser; or it can be a simple heat transport circuit without a compressor.

An expansion valve (for example an electronic expansion valve) can be provided upstream of the heat exchanger 408' in this secondary circuit.

A pump may be provided in this secondary circuit to circulate the additional heat transfer composition.

The additional heat transfer composition may optionally change state, in whole or in part, upon passing through the heat exchanger 408'. Thus, if the heat transfer composition is cooled in the heat exchanger 408', the additional heat transfer composition is correspondingly heated and can evaporate in whole or in part (for example from a completely liquid state to a biphasic liquid-vapor state). Conversely, if the heat transfer composition is reheated in the heat exchanger 408', the additional heat transfer composition is correspondingly cooled and can condense in whole or in part (for example from a two-phase liquid-vapor state). to a completely liquid state). Optionally, the secondary circuit can be reversible (ie it can cool or heat the heat transfer composition which is in contact with the battery, depending on the mode of operation).

The heat exchanger 408′ allowing the exchange of heat with the additional heat transfer composition can for example be co-current or, preferably, counter-current.

The term "countercurrent heat exchanger" means 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.

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, or nearly opposite, directions. Exchangers operating in cross-flow mode with counter-current tendency are also included among counter-current heat exchangers.

The heat exchangers may in particular be exchangers with U-tubes, horizontal or vertical tube bundles, spirals, plates or fins.

The additional heat transfer composition itself can exchange heat with the environment, by means of an additional heat exchanger. It can optionally also be used to heat or cool the air in the vehicle interior. Thus, the heat dissipated by the battery can be absorbed by the vehicle's air conditioning circuit.

To this end, the secondary circuit may comprise different branches equipped with separate heat exchangers, the additional heat transfer composition circulating or not in these branches, depending on the mode of operation. Optionally, alternatively or in addition, the secondary circuit may comprise means for changing the direction of circulation of the additional heat transfer composition, comprising for example one or more three-way or four-way valves.

The main circuit may include a reservoir for storing excess heat transfer composition in liquid form.

The secondary circuit may include a reservoir for storing excess additional heat transfer composition in liquid form. When the main circuit is equipped with a pump, a protection can be provided for example upstream of the pump, to ensure that only liquid is pumped towards the battery. Indeed, depending on the external conditions (for example when the vehicle is hot on start-up due to weather conditions), the heat transfer composition may be two-phase upstream of the pump, in particular at the outlet of the tank. The protection can include a bypass system, in particular between the tank and the pump, with a valve, a pressure sensor and a temperature sensor. A filter and dryer may be provided to capture impurities and moisture respectively.

It is possible to provide a third circuit containing another additional heat transfer composition, thermally connected to the secondary circuit, by a heat exchanger. This third circuit can in particular be dedicated to recovering the heat dissipated by the engine and/or the electrical components of the vehicle.

It is possible to provide two or more main circuits operated in parallel and controlled independently, to regulate the temperature of different modules of the battery, or to control different batteries when there are several.

A battery management system 410 can be associated with battery 402, in order to measure the electrical parameters (in particular the voltage) but also the temperature of each module (by means of temperature sensors), and control the modules as well as the main circuit (and possibly the secondary circuit), and in particular their pumps, in order to ensure that the electrical parameters in question and the temperature are within the desired ranges.

Specific examples of thermal regulation systems comprising a main circuit and a secondary circuit are now described in more detail.

Referring to Figure 2, an example of a battery assembly according to the invention (usable in particular in a vehicle) comprises a thermal regulation system 1 which comprises a main circuit 2 containing the heat transfer composition described above and a secondary circuit 3 containing an additional heat transfer composition, the two circuits being thermally connected by at least one heat exchanger 4. The heat transfer composition in the main circuit 2 is moved by a pump 7 or by natural convection. The additional heat transfer composition in the secondary circuit 3 is set in motion by a pump 8. The secondary circuit 3 comprises an expansion valve 9 making it possible to ensure the evaporation of the additional heat transfer composition in the heat exchanger 4, in order to cool the heat transfer composition of the main circuit 2.

At least one battery module 10 (as described above) is fluidly integrated into the main circuit 2. A heating element 11 can be associated with the battery module 10 or integrated into it.

When the circuit is equipped with a pump, a tank 21 can optionally be provided in the main circuit 2 to receive an excess of heat transfer composition in liquid form.

In battery cooling mode, the pump 7 takes the heat transfer composition from the tank 21 and sends it to the battery module 10. The heat transfer composition is in the liquid state at the inlet of the battery module. battery 10. It reaches its saturation temperature and is partially vaporized by passing through the battery module 10 and by absorbing the heat dissipated by the cells. It leaves the battery module 10 in a biphasic liquid-vapor state. The battery module 10 thus acts as an evaporator with respect to the main circuit.

The two-phase heat transfer composition then passes through the heat exchanger 4. The additional heat transfer composition is expanded in the expansion valve 9 and then totally or partially vaporizes in the heat exchanger 4. The transfer composition heat condenses transferring heat to the additional heat transfer composition. The heat transfer composition in liquid form then returns to the tank 21 .

The secondary circuit 3 may be the automotive air conditioning circuit of the vehicle (the compressor not being shown in the figure).

Referring to Figures 3 and 4, an example of a battery assembly according to the invention (usable in particular in a vehicle) comprises a thermal regulation system 1 which comprises a main circuit 2 as previously described and a secondary circuit 3 capable of operate as a reversible heat pump. Thus, the battery module 10 can be cooled and heated by the heat transfer composition. The secondary circuit has two operating modes: a cooling mode and a heating mode. The cooling mode is shown in figure 3 and the heating mode is shown in figure 4.

The secondary circuit 3 comprises an HVAC module 16 (heating, ventilation and air conditioning) ensuring the thermal regulation of the air in the I passenger compartment. It comprises a condenser 17 and an evaporator 18. The condenser 17 is used to heat the air in the passenger compartment and the evaporator 18 is used to cool it.

The secondary circuit 3 further comprises a control valve 19, a shut-off valve 24, a tank 37 and an external heat exchanger 20. An expansion valve 9 is arranged downstream of the external heat exchanger 20 and a calibrated orifice 25 with shut-off function is arranged upstream of evaporator 18. Expansion valve 9, shut-off valve 24 and calibrated orifice 25 can be controlled electrically. The control valve 19 can be a reversible valve and/or a four-way valve capable of changing the direction of circulation of the additional heat transfer composition.

In cooling mode, the control valve 19 is in a first position such that the external heat exchanger 20 is used as a condenser while the heat exchanger 4 and the evaporator 18 are used as evaporators. Shut-off valve 24 and calibrated orifice 25 are open in this mode. The additional heat transfer composition in reservoir 37 is in a biphasic state and pump 8 directs it to the external heat exchanger 20. The additional heat transfer composition condenses therein and is directed outward. heat exchanger 4 and evaporator 18. In both cases, it is at least partially vaporized and returned to tank 37.

In heating mode, the control valve 19 is in a second position such that the external heat exchanger 20 is used as an evaporator while the heat exchanger 4 and the condenser 17 are used as condensers. Shut-off valve 24 and calibrated orifice 25 are closed in this mode. The additional heat transfer composition in reservoir 37 is in a two-phase state and pump 8 directs it to condenser 17 where it is partially condensed. Then it goes to heat exchanger 4 where it continues to condense. Then it passes through the external heat exchanger 20 having an evaporator function.

Optionally, a third circuit 12 can be provided and intervene in heating mode. The third circuit 12 can make it possible to recover heat dissipated by a motor 26 and/or electrical components 22 of the vehicle. It may include a pump and a radiator 28. A bypass provided with a shut-off valve 29 can allow the bypass of the radiator 28. The third circuit 12 is thermally connected to the secondary circuit 3 by a second heat exchanger 13. The third circuit can by example include a fluid of the mixture of water and glycol. In heating mode, the additional heat transfer composition, at the outlet of the heat exchanger 4, is distributed in the external heat exchanger 20 and in the second heat exchanger 13, both of which have an evaporator function. It therefore absorbs the heat dissipated by the fluid of the third circuit 12.

The secondary circuit 3 may comprise two non-return valves 23 on the branch of the circuit comprising the second heat exchanger 13 (in parallel with the branch comprising the external heat exchanger 20), as well as an expansion valve 9 upstream of the second heat exchanger 13.

Temperature regulation

The invention relates to the use of a heat transfer composition according to the invention for cooling the battery. However, the composition can also be used, at other times, to heat the battery and remains mainly in liquid form. Heating and cooling can be alternated as needed (outdoor temperature, battery temperature, battery operating mode). Heating the battery is useful in particular when starting the vehicle, when the outside temperature is cold (for example below 10° C., or 0° C., or -10° C., or -20° C.).

The heating can also be carried out at least in part, or even entirely, by means of an auxiliary heating element, for example an electrical resistor. The auxiliary heating element can be mounted on the battery.

It is thus possible to dedicate the heat transfer composition according to the invention solely to cooling the battery in a uniform manner, while other means, for example an electrical resistor, are used for its heating.

Alternatively, it is possible to provide a heating element associated with the main circuit, in particular upstream of the battery. In this case, the heating element is likely to heat the heat transfer composition, which then heats the battery.

By "battery temperature" is generally meant the temperature of an outer wall of one or more of its electrochemical cells.

Battery temperature can be measured using a temperature sensor. If several temperature sensors are present at the level of the battery, the temperature of the battery can be considered as being the average of the various temperatures measured. The invention makes it possible to considerably reduce the difference between the temperatures measured at different points of the battery.

Temperature regulation can be performed while the vehicle battery is charging. Alternatively, it can be performed when the battery is discharging, in particular when the vehicle engine is on. In particular, it prevents the temperature of the battery from becoming excessive, due to the outside temperature and/or due to the actual heating of this battery during operation.

In particular, the battery charge can be a fast charge. Thus, when fully charging the battery (from a moment when the battery is completely discharged) for a period of less than or equal to 30 min, and preferably less than or equal to 15 min, the use of the composition according to the invention makes it possible to maintain the temperature of the battery in an optimum temperature range with a uniform distribution. This has an advantage given that during a fast charge, the battery tends to heat up quickly and reach high temperatures with in particular hot spots which can degrade its operation, its performance and reduce its lifespan.

In some embodiments, the cooling of the battery is continuous over a period of time.

In certain embodiments, the cooling and optionally the heating make it possible to maintain the temperature of the battery within an optimum temperature range, in particular when the vehicle is in operation (engine on), and in particular when the vehicle is moving. Indeed, if the battery temperature is too low, its performance is likely to decrease significantly.

In certain embodiments, the temperature of the battery of the vehicle can thus be maintained between a minimum temperature ti and a maximum temperature t2.

In some embodiments, the minimum temperature ti is greater than or equal to 10°C and the maximum temperature t2 is less than or equal to 80°C, preferably the minimum temperature ti is greater than or equal to 15°C and the maximum temperature t2 is less than or equal to 70°C, and more preferably the minimum temperature ti is greater than or equal to 16°C and the maximum temperature t2 is less than or equal to 50°C. By example, ti may be equal to 20°C (or even greater than 20°C) and t2 may be equal to 40°C (or even less than 40°C).

A feedback loop is advantageously present, to modify the operating parameters of the installation according to the temperature of the battery which is measured, in order to ensure the maintenance of the temperature which is desired.

The outside temperature for the duration of the maintenance of the temperature of the battery of the vehicle between the minimum temperature ti and the maximum temperature t2 can in particular be from -60 to -50° C.; or -50 to -40°C; or -40 to -30°C; or -30 to -20°C; or -20 to -10°C; or -10 to 0°C; or from 0 to 10°C; or 10 to 20°C; or 20 to 30°C; or 30 to 40°C; or 40 to 50°C; or 50 to 60°C; or 60 to 70°C.

“Exterior temperature” means the ambient temperature outside the vehicle before and during the maintenance of the temperature of the vehicle battery between the minimum temperature ti and the maximum temperature t2.

The invention also relates to the use of the heat transfer composition described above, to prevent, to delay or to limit the consequences of runaway of the battery following a failure (for example a short circuit). The presence of a runaway is characterized by an uncontrolled increase in temperature accompanied by a rapid generation of gas caused mainly by the decomposition of the electrolyte, at a typical temperature of 150 to 200°C, leading to the formation of CO, CO2, HF and flammable species such as H2, CH _4J C2H4, C2H6, C2H5F. The flammable gas content can reach at least 30 mol. % in the ejected gases.

Thus, the heat transfer composition described above can be used to maintain the temperature of the battery below 150°C, preferably below 140°C, more preferably below 140°C, even more preferably below 130°C, in case of failure.

The heat transfer composition described above can also be used to reduce or eliminate the flammability of the gaseous mixture ejected in the event of battery runaway. In particular, it can be used to ensure that the content of flammable gases in the ejected gas mixture remains relatively low. It can be used to ensure that the refrigerant content in the ejected gas mixture is greater than or equal to 30 mol. %, preferably greater than or equal to 40 mol. %, or at 50 mol. %, or at 60 mol. % or 70 mol. %; in this embodiment, this refrigerant is chosen to be non-flammable, i.e. class A1 in the ASHRAE 34 standard; preferably the refrigerant comprises or consists of HCFO-1233zdE.

Compositions were prepared by combining HCFO-1233zdE as refrigerant with a mixture of benzyltoluene and dibenzyltoluene (marketed by Arkema under the name Jarylec® C101). It was previously verified that the two products were miscible in all proportions.

The oil was loaded by weighing into a 0.2 L autoclave equipped with a magnetic stirrer and a jacket in which circulates a heat transfer fluid so as to homogenize the temperature in the gas phase and the liquid phase.

The autoclave was then cooled to -10°C where the vacuum was pulled.

The HCFO-1233zdE contained in a cylinder was transferred in a closed circuit in the liquid phase by weighing.

The minimum volume of loaded liquid was calculated so that the composition of the liquid phase does not vary as a function of temperature.

The final mixture was brought to the desired temperature with stirring in order to homogenize it. The agitation was then turned off until the mixture reached equilibrium. Temperature and pressure were measured at equilibrium.

Figure 5 illustrates the influence of the refrigerant content on the liquid saturation temperature of the composition at a saturation vapor pressure of 1 bar. More particularly, it is found that compared to a composition comprising 100% oil, the addition of refrigerant to the composition, even in a low content, makes it possible to significantly reduce the liquid saturation temperature of the composition, which allows to increase the cooling capacity of the battery.

A composition was prepared by mixing 69.2 g of HCFO-1233zd E and 100.5 g of Jarylec®C101 from the company Arkema, under the conditions presented above. [Table 1]

Another composition was prepared by mixing 35% by weight of HCFO-1233zdE and 65% by weight of Jarylec®C101, from Arkema, under the conditions presented below.

The breakdown voltage was measured according to IEC 60159:1995.

[Table 2]

Example 2 - viscosity

Viscosity measurements were carried out in a jacketed autoclave reactor in which circulates a heat transfer fluid, with a capacity of 0.2 L, into which Jarylec®C101 oil was introduced. The reactor is brought cooled to −10° C. and stirred magnetically. Then, HCFO-1233zdE was introduced by pressure difference. The reactor was then brought to the measurement temperature.

Viscosity was then measured using a SOFRASER vibrating rod viscometer, model MIVI 9601. A camera was used to confirm the miscibility of the oil and the refrigerant under the measurement conditions and to check the immersion of the viscometer rod, before carrying out the measurement.

[Table 3] By way of comparison, a viscosity measurement according to the ISO 3104 standard was carried out on the oil (0% of HCFO-1233zd E) at 20°C. The value obtained is 6.5 cP.

Example 3 - flammability

A flash point measurement was carried out on a composition containing 90% by weight of Jarylec®C101 oil and 10% by weight of HCFO-1233zdE, as well as on a comparative composition containing 100% by weight of Jarylec®C101 oil.

The mixture was prepared at low temperature, under atmospheric pressure. It is homogeneous and liquid at room temperature and atmospheric pressure.

The flash point measurement was performed according to ISO 3679 or ISO 3680, "Pass/Fail-Type Flash Point Test - Rapid Closed Cup Equilibrium Method." The standardized tests are carried out with the filling orifice left free, therefore open and breathing the atmosphere, the cup being closed.

The tests were adapted depending on the case by plugging the filling orifice so as to be able to simulate an even more confined device during temperature equilibrium (2 minutes under standardized conditions). In this case, the tests are carried out "clogged lid".

The temperature range explored was up to 300°C.

[Table 4]

Example 4 - heat transfer coefficient (two-phase immersion)

In order to perform heat transfer coefficient measurements, a test device placed in a thermal regulation chamber is used to measure the performance of fluids by varying the ambient temperature. The test device includes a container with a heating element and a condenser. The condenser is located at the top of the vessel and is cooled by a chilled water loop. The heating element is a cylindrical resistor with a diameter of 15 mm and a height of 80 mm in a copper sheath, which is immersed vertically in a cylinder filled with saturated liquid in order to heat it. It can supply up to 15 W/cm ² . Eight sensors temperature are placed on the copper board to measure the surface temperature.

Two different mixtures of an oil whose properties, in particular viscosity, are close to those of Jarylec®C101 oil, and whose properties, in particular thermal properties (thermal conductivity greater than 0.05 W/(m ² .K) and The dielectrics meet the specifications for this application, and HCFO-1233zdE was tested. The HCFO-1233zdE was introduced first avoiding any entry of moisture or air pollution. The oil was added by gravity with a graduated cylinder Miscibility and homogeneity were checked by sampling.

The temperature of the cooling water (temperature of 10°C at the condenser) and the flow rate were set at the desired values. The room temperature was set at 26°C. The thermal power was increased from 0 to 90 W in 5 W increments, then decreased again for hysteresis detection. An average value of the heat transfer coefficient was measured during the temperature rise: H= F/(T _W -Tsat), with F the heat flux density, T _w the temperature of the wall, and Tsat the temperature of the liquid saturation of the measured composition.

[Table 5]

Example 5 - runaway prevention

A test was carried out in a compact assembly of 8 energy storage cells, housed in a sealed enclosure filled with fluid A (pure HCFO-1233zdE) or fluid B (60% HCFO-1233zdE + 40 % aliphatic hydrocarbon dielectric oil, by mass). The enclosure is fitted with a valve calibrated for a pressure greater than the vapor pressure of the fluid at 50°C.

The test is equipped with thermocouples for monitoring cell wall and fluid temperatures. The ejected gases are analyzed by gas phase chromatography after washing to remove the acid products. The characteristics of the cells are as follows:

- Model: Samsung INR 18650 35E.

- Electrical architecture: 1s8p.

- Capacity: 3.5 A.h.

- Chemistry: LiNiCoMnO2.

- Electrical voltage: 2.5 V minimum, 3.6 V nominal, 4.2 V maximum.

At time t=0, a short circuit is created on one of the cells charged to the maximum by means of a nail. The cell concerned then undergoes a thermal runaway, which results in an increase in pressure and an opening of the containment valve.

In the case of fluid A, the valve calibration pressure is 4 bar absolute. The content of HCFO-1233zd in the ejected gases is more than 60 mol. %.

Gas analysis does not reveal any degradation of HCFO-1233zd.

The runaway does not spread to other cells, which remain intact.

In the case of fluid B, the valve calibration pressure is 3 bar absolute. The content of HCFO-1233zd in the ejected gases is more than 50 mol. %. The runaway does not spread to other cells, which remain intact. Gas analysis does not reveal any degradation of HCFO-1233zd, nor any reaction with the oil.

Claims

37

Claims

1. Use of a heat transfer composition comprising from 20% to less than 100% by weight of a refrigerant comprising a compound chosen from halogenated hydrocarbons, perhalogenated compounds, fluorinated ketones, fluorinated ethers and their combinations, and greater than 0% to 80% by weight of a dielectric fluid, for cooling a battery, the battery comprising energy storage cells immersed in the heat transfer composition, and the heat transfer composition undergoing evaporation on contact with the energy storage cells.

2. Use according to claim 1, wherein the heat transfer composition circulates in a heat transfer circuit.

3. Use according to claim 2, in which the battery comprises one or more modules each comprising an enclosure in which energy storage cells are arranged, the enclosure(s) forming part of the heat transfer circuit.

4. Use according to claim 2 or 3, wherein the heat transfer circuit is thermally coupled to a secondary circuit containing an additional transfer composition.

5. Use according to claim 4, wherein the secondary circuit is the air conditioning circuit of a vehicle; and/or is a reversible heat pump circuit.

6. Use according to one of the preceding claims, in which the refrigerant comprises or is 1-chloro-3,3,3-trifluoropropene, preferably in the E form, or is a binary mixture, preferably azeotropic, of 1 -chloro-3,3,3-trifluoropropene in the Z form and of 1, 1, 1, 2,3- 38 pentafluoropropane, or 1,1,1,4,4,4-hexafluorobut-2-ene in the Z form and 1,2-dichloroethylene in the E form. Use according to one of the preceding claims, in which the dielectric fluid is chosen from mineral dielectric oils, synthetic dielectric oils, and vegetable dielectric oils, and preferably from aromatic hydrocarbons chosen from alkylbenzenes, alkyldiphenylethanes, alkylnaphthalenes, methylpolyarylmethanes and combinations thereof, poly(alpha)olefins and polyol esters. Use according to one of the preceding claims, in which the battery is the battery of an electric or hybrid vehicle, preferably of an electric or hybrid automobile. Use according to the preceding claim, implemented when charging the battery of the vehicle, the battery of the vehicle preferably being fully charged in a period less than or equal to 30 min, and preferably less than or equal to 15 min from its total discharge. Battery assembly, in particular for an electric or hybrid vehicle, comprising one or more modules each comprising an enclosure in which are arranged energy storage cells immersed in a heat transfer composition, the heat transfer composition comprising 20% less than 100% by weight of a refrigerant comprising a compound chosen from halogenated hydrocarbons, perhalogenated compounds, fluorinated ketones, fluorinated ethers and combinations thereof, and from more than 0% to 80% by weight of a dielectric fluid, the battery assembly being configured such that the heat transfer composition undergoes evaporation to cool the battery. A battery assembly according to claim 10, comprising a heat transfer circuit in which the composition circulates of heat transfer, the enclosure(s) of the module(s) being integrated into this heat transfer circuit.

12. A battery assembly according to claim 11, wherein the heat transfer circuit comprises a pump; and/or wherein the heat transfer circuit includes a heat exchanger to allow heat exchange of the heat transfer composition either with ambient air or with a heat transfer composition in a secondary circuit.

13. Battery assembly according to one of claims 10 to 12, in which the refrigerant comprises or is 1-chloro-3,3,3-trifluoropropene, preferably in the E form, or is a binary mixture, preferably azeotropic, of 1-chloro-3,3,3-trifluoropropene in the Z form and of 1, 1,1, 2,3-pentafluoropropane, or of 1,1,1,4,4,4-hexafluorobut-2-ene in the Z form and 1,2-dichloroethylene in the E form.

14. Battery assembly according to one of claims 10 to 13 wherein the dielectric fluid is chosen from mineral dielectric oils, synthetic dielectric oils, and vegetable dielectric oils, and preferably from alkylbenzenes, alkyldiphenylethanes, alkylnaphthalenes , methylpolyarylmethanes and combinations thereof, poly(alpha)olefins and polyol esters.

15. A method of regulating the temperature of the battery of the battery assembly according to one of claims 10 to 14, comprising cooling the energy storage cells by the heat transfer composition by partial evaporation of the composition of heat transfer.