Thermal fluid comprising particles of at least one thermomass material

Abstract

The invention relates to a thermal fluid comprising solid particles of at least one thermomass material having a solid-solid phase change under the action of at least one external physical field, preferably a magnetic field, an electric field and / or a mechanical field. The invention also relates to the use of a fluid as a heat transfer fluid, preferably in thermodynamic systems or applications involving heat transfer. The invention also relates to a composition comprising a thermal fluid as defined previously. The invention also relates to a thermal system comprising at least one composition, at least one heat source heat exchanger, at least one cold source heat exchanger and at least one means capable of applying at least one physical field, preferably a magnetic field, an electric field and / or a mechanical field, said physical field being capable of inducing a solid-solid phase change within a thermomass material.

Description

[0001] The present invention relates to a thermal fluid comprising solid particles of at least one caloric material, wherein the caloric material has a solid-solid phase change under the action of at least one external physical field (preferably a magnetic field, an electric field and / or a mechanical field).

[0002] The invention also relates to a composition comprising at least one thermal fluid as defined above.

[0003] Another object of the present invention is the use of a composition as defined below as a heat transfer fluid, preferably in thermodynamic systems or applications involving heat transfer.

[0004] The present invention also relates to a thermal system comprising at least one composition as defined below or a fluid as defined below, at least one heat source heat exchanger, at least one heat sink heat exchanger, and at least one device capable of applying at least one physical field (preferably magnetic, electric and / or mechanical field) capable of inducing a solid-solid phase change in a thermal mass material.

[0005] The present invention also relates to a method of heat transfer comprising circulating a composition as described below or a fluid as described below and applying at least one external physical field capable of inducing a solid-solid phase change in a thermal mass material of the composition.

[0006] Heat transfer is generally at the heart of many industrial and residential systems designed for a variety of applications involving the generation of heat or cooling.

[0007] Most of these systems are primarily directed to the heat exchange work that occurs during the liquid-vapor state changes of a refrigerant (also called a working fluid) that undergoes a compression and expansion cycle.

[0008] For example, in a cycle within a refrigeration system, a working fluid in vapor phase is first compressed by a compressor and then liquefied at a constant temperature and pressure in a condenser. As the refrigerant changes from vapor to liquid in the condenser, the refrigerant releases heat to the external environment due to its reduced entropy. Once the refrigerant has changed state, the refrigerant in liquid form is directed to an expansion valve, where its pressure is reduced and then directed toward an evaporator to vaporize. When the refrigerant changes from a liquid state to a vapor in the evaporator, the refrigerant receives heat from the environment to be cooled because its entropy increases. The refrigerant is eventually redirected toward the compressor to start a new condensation and evaporation cycle. In this way, during the refrigeration cycle, the working fluid vaporizes in the evaporator by absorbing thermal energy provided by the heat of the environment to be cooled (e.g., the interior of a refrigerator). This thermal energy is then released to the external environment as the fluid circulates in the condenser.

[0009] Refrigeration systems, especially those used in the medical, electronics and agri-food sectors, as well as air conditioning systems in the transport sector, generally rely on this type of technology.

[0010] Similarly, heating systems, such as those using heat pumps, operate on the same principle of heat exchange, which occurs during a continuous cycle of evaporation and condensation of a refrigerant as it changes from a liquid to a vapor state.

[0011] However, this technology has a certain number of disadvantages, in particular those associated with risks and the need to comply with refrigerant quality, health, safety and environmental standards, which requires close monitoring of the use of refrigerants. In fact, such fluids can be harmful to health, including the risk of inflammation and contribute to climate warming.

[0012] In addition, thermal systems that rely on this type of technology to operate consume a lot of energy. In other words, the overall energy efficiency of this type of system is not satisfactory at this time.

[0013] In order to cope with the problems raised, especially in terms of the growing environmental and energy challenges, alternative heat transfer solutions have been developed, in particular based on phase transitions from one solid state to another of thermal mass materials induced by the action of specific external physical fields (e.g. magnetic fields, electric fields or mechanical stresses such as pressure stress).

[0014] In other words, thermal systems have been developed that exploit the thermal effects generated by thermodynamic changes within a material under the action of magnetic or electric fields or even mechanical stresses (such as pressure stress) with the aim of competing with current thermal systems based on continuous evaporation and condensation cycles of a working fluid.

[0015] Such solid thermal mass materials may correspond to magnetic thermal mass, electric thermal mass or mechanical thermal mass materials comprising multiple solid phases.

[0016] The thermal effect of this material is notably reversible when the induced external physical field is removed.

[0017] Among them, piezoelectric materials, i.e. materials that undergo solid-solid phase transitions under the action of pressure stress, have recently attracted great interest because the thermal effects obtained can be significant in view of the applied pressure stress, which is relatively low and easier to control than magnetic or electric fields.

[0018] For example, recent studies have shown that neopentyl glycol crystals can deform under relatively low compressive stress, in particular transforming from a disordered crystalline phase to an ordered phase, and return to their original shape when the stress is removed, while releasing or absorbing heat during these solid-solid phase changes. These crystals have a so-called "plastic" structure and exhibit cooling properties comparable to those of standard refrigerants.

[0019] However, one of the technical difficulties of these alternative solutions is in particular the one-sided, continuous or semi-continuous heat transfer from the cold source to the hot source of the system in order to achieve efficient energy transfer.

[0020] In fact, the application of an external physical field causes a decrease in the entropy within the thermal mass material, such as a decrease in the entropy of the dipoles in the case of an electric field or the creation of an ordered crystalline phase in the case of a pressure stress, which causes heat to be transferred to the cold source. Alternatively, when the external physical field is removed, the entropy of the material increases, such as the orientation of the dipoles becomes more random in the case of the electric field or returns to a more disordered crystalline phase in the case of the pressure stress, which causes heating and therefore heat to be transferred from the outside to the material.

[0021] Therefore, one of the technical difficulties of this solution is to minimize the movement back and forth between the material and the heat sink during the alternation of the applied physical field and to ensure that the material absorbs energy in the heat sink in order to produce an efficient transfer of energy from it to the heat source.

[0022] To this end, currently proposed solutions involve the use of thermal enclosures with thermal mass materials in the solid state, associated with a system of thermal diodes that ensure a unidirectional heat transfer of heat. Such thermal diodes may, for example, take the form of microchannels or pressurized fluid exchangers.

[0023] More generally, the fact that the thermal mass material constitutes a static thermal mass solution requires the use of complex and expensive heat removal systems, the efficacy of which may prove to be limited.

[0024] Furthermore, it has been observed that thermal mass materials, especially pressure thermal mass materials, can exhibit significant temperature hysteresis loops, making their use in industrial systems problematic. This means that in the case of pressure thermal mass materials, the structural deformation curve when the pressure stress is removed does not follow the same path as when the pressure stress was applied.

[0025] In view of the above, one of the objects of the present invention is to overcome the above disadvantages, in particular to achieve efficient heat transfer between the cold and hot sources of the thermal system and the thermal mass materials, so as to obtain performance comparable to that of current thermal systems while minimizing negative impacts on the environment and health.

[0026] In other words, there is a real need to come up with a solution that facilitates the heat transfer between the hot and cold sources of a thermal system in order to obtain an efficient thermal system, especially in terms of performance and energy efficiency, while remaining viable from an environmental and health point of view.

[0027] In particular, one of the objects of the invention is to improve current solutions or technical applications based on heat transfer occurring during a phase change of a thermal mass material from a solid state to another solid state caused by the action of a specific external physical field.

[0028] Therefore, one object of the present invention is in particular a thermal fluid comprising solid particles of at least one thermal mass material having a thermal conductivity greater than or equal to 100 J.K under the action of at least one external physical field. -1 .kg -1 The absolute entropy change ΔS varies from 2 wt% to 98 wt% relative to the total weight of the fluid.

[0029] The fluid according to the invention effectively facilitates heat transfer between the heat source and the heat sink of a thermal system, thereby ensuring that it has performance comparable to current thermal systems while minimizing negative impacts on the environment and health.

[0030] In particular, at least one physical field, preferably a magnetic field, an electric field and / or a mechanical field, is applied so as to activate a solid-solid phase transition of particles of at least one thermal mass material as defined above immersed in a fluid, thereby causing a heat exchange in the fluid. This results in heat conduction between the particles of the thermal mass material, the fluid and the heat source and the heat sink of the thermal system, thereby generating a working cycle.

[0031] The fluid according to the invention has the advantage, inter alia, that it is able to transport thermal mass material in the form of solid particles immersed in the fluid, thereby shifting the point at which the material absorbs heat and the location at which it releases heat and improving heat transfer.

[0032] Thus, the fluid according to the present invention enables thermal mass materials in systems or thermodynamic applications involving heat transfer to be not fixed or stationary, but moving in the form of a flowing fluid.

[0033] The fluid according to the invention therefore has the advantage of minimizing the back and forth movement between the material and the heat sink during the alternation of the applied physical field.

[0034] The fluid according to the invention thus enables efficient use of the thermal effects of materials, in particular magnetocaloric, electrocaloric and / or mechanocaloric effects, while minimizing the heat transfer losses that may occur in thermodynamic systems involving heat transfer.

[0035] Furthermore, fluids according to the invention can be used to minimize hysteresis previously observed in thermal systems using static thermal mass (particularly autoclave) materials, ie materials that do not move between the heat source and the heat sink of the system.

[0036] In other words, the present invention provides a thermal mass material in particulate form in a fluid to produce improved heat transfer between a heat source and a heat sink in a thermal system. In this way, the fluid can be used to transfer heat between multiple temperature sources, which makes it possible to dispense with the installation of devices designed to remove heat from the thermal mass material.

[0037] The invention also relates to the use of a fluid as defined above as a heat transfer fluid, in particular in thermodynamic systems involving heat transfer.

[0038] The invention also relates to a composition comprising at least one thermal fluid as defined above.

[0039] In other words, the composition according to the invention comprises at least one thermal fluid mixed with solid particles of at least one thermal mass material having a thermal conductivity greater than or equal to 100 J.K under the action of at least one external physical field. -1 .kg -1 The absolute entropy change ΔS is , and its content varies between 2 wt % and 98 wt % relative to the total weight of the fluid.

[0040] Another subject of the present invention is the use of the composition as defined above for transferring heat, preferably in a thermodynamic system involving heat transfer.

[0041] Similarly, the present invention also relates to a thermal system comprising at least one composition as described above or a fluid as defined above, at least one heat source heat exchanger, at least one cold source heat exchanger and at least one device for applying at least one physical field capable of causing a thermal shock greater than or equal to 100 J.K in the thermal mass material of the fluid. -1 .kg -1 The absolute entropy change ΔS.

[0042] The thermal system according to the invention has particularly advantageous energetic properties.

[0043] Another object of the present invention is to provide a heat transfer method, which comprises at least circulating the composition as defined above or the fluid as defined above between at least one heat source heat exchanger and at least one cold source heat exchanger, and at least applying a physical field to induce a heat transfer greater than or equal to 100 J.K in the thermal mass material of the fluid. -1 .kg -1 The absolute entropy change ΔS.

[0044] This approach is particularly advantageous because it enables heat transfer without the need for a system for rejecting heat to a temperature source in the system.

[0045] Other characteristics and advantages of the invention will become more apparent on reading the following description and examples.

[0046] In the following, and unless otherwise stated, the limits of a range of values ​​are included in the range.

[0047] The term "at least one" is equivalent to the term "one or more".

[0048] liquid

[0049] As mentioned above, the thermal fluid comprises solid particles of at least one thermal mass material having a thermal conductivity greater than or equal to 100 J.K under the action of at least one external physical field. -1 .kg -1 The absolute entropy change ΔS varies from 2 wt% to 98 wt% relative to the total weight of the fluid.

[0050] According to the present invention, the external physical field corresponds to an external stress applied at a level sufficient to induce a solid-solid phase transition in the thermomass material, such as a change in dipole orientation when an electric field is applied, or a structural change from a disordered crystalline phase to an ordered crystalline phase when a pressure stress or a magnetic field is applied.

[0051] According to the present invention, external stresses of various natures may be applied to induce solid-solid phase changes within the thermal mass material.

[0052] According to the present invention, the solid-solid phase change in the thermal mass material results in a material having a thermal conductivity greater than or equal to 100 J.K -1 .kg -1 The absolute entropy change ΔS value.

[0053] The entropy change ΔS can be measured using a calorimeter capable of applying a stress field within the test cell.

[0054] For example, in a pressure field calorimeter, the 8 The autoclave effect was evaluated in units of pressure of 100 Pa.

[0055] The electrocaloric effect is evaluated, for example, in electric field calorimeters.

[0056] The magnetocaloric effect is evaluated, for example, in magnetic field calorimeters.

[0057] The thermal sensor is used to measure the heat exchange in the calorimeter cell when a stress field is applied. The temperature in the cell is controlled by a heating bath outside the cell. The calorimetric measurement gives a dQ / dT value for each temperature. The integral of the values ​​dQ / dT and 1 / T.dQ / dT is used to determine the enthalpy and entropy, respectively, of the solid / solid phase change produced by the application of the stress field in the measuring cell.

[0058] The absolute entropy change ΔS of the thermal mass material can also be greater than or equal to 200 J.K -1 .kg -1 , preferably greater than or equal to 300 J.K -1 .kg -1 .

[0059] The absolute entropy change ΔS of the thermal mass material can preferably be 100 J.K -1 .kg -1 Up to 1000J.K -1 .kg -1, more preferably 200 J.K -1 .kg -1 Up to 800J.K -1 .kg -1 , more preferably 300 J.K -1 .kg -1 Up to 700J.K -1 .kg -1 within the range.

[0060] The absolute entropy change ΔS of the thermal mass material preferably occurs at a temperature in the range of 231K to 420K, preferably in the range of 233K to 400K, and more preferably in the range of 273K to 320K.

[0061] The external physical field is preferably applied at a temperature as defined above.

[0062] The external physical field may preferably be an electric field, a magnetic field and / or a mechanical stress.

[0063] Thus, the thermal mass material present in the composition according to the invention may be a magnetic thermal mass, an electrical thermal mass and / or a mechanical thermal mass material.

[0064] Mechanical stress may correspond to the application of a tensile force (particularly in the case of materials with entropic elasticity), or to stress caused by a pressure change.

[0065] The physical field is more particularly a mechanical stress. In other words, the physical field is particularly a mechanical stress field.

[0066] The mechanical stress is preferably a pressure stress, ie a pressure field which induces a solid-solid phase transition within the thermal mass material.

[0067] In the case of a mechanocaloric material, the material may be elastocaloric or pressure-caloric, preferably pressure-caloric.

[0068] The external physical field is preferably an electric field and / or pressure stress (or pressure stress field), more preferably pressure stress.

[0069] Thus, the thermal mass material present in the fluid may be an electric thermal mass and / or a piezo thermal mass material, preferably a piezo thermal mass.

[0070] The fluid preferably comprises solid particles of at least one pressure caloric material having a thermal conductivity greater than or equal to 100 J.K under pressure stress. -1 .kg -1 The absolute entropy change ΔS varies from 2 wt% to 98 wt% relative to the total weight of the fluid.

[0071] The fluid preferably comprises solid particles of at least one pressure caloric material having a thermal conductivity greater than or equal to 100 J.K under pressure stress.-1 .kg -1 The absolute entropy change ΔS, whose content varies from 10 wt % to 90 wt %, preferably from 20 wt % to 80 wt %, more preferably from 30 wt % to 70 wt %, and still more preferably from 40 wt % to 60 wt %, relative to the total weight of the fluid.

[0072] Furthermore, the thermal mass material may be particularly insoluble in the fluid of the composition according to the invention.

[0073] The thermal mass material may be an organic material, an inorganic material, or an organic-inorganic hybrid material.

[0074] The thermal mass material can be selected from plastic crystals, in particular plastic crystals derived from neopentane containing amine functional groups, hydroxyl functional groups and mixtures thereof, in particular neopentyl glycol, 2-amino-2-(hydroxymethyl)propane-1,3-diol, 2-amino-2-methyl-1,3-propanediol, 2-hydroxymethyl-2-methyl-1,3-propanediol, 2,2-dimethyl-1-propanol; salts, such as ferroelectric salts, ammonium salts, in particular ammonium iodide, ammonium sulfate; organic-inorganic hybrid compounds such as organic perovskites, intermetallic compounds (for example based on transition metals such as iron, copper, cobalt, titanium, nickel, zirconium, manganese, rhodium, based on poor metals such as aluminum, zinc, lead, based on metalloids such as germanium, silicon, boron, based on alkaline earth metals such as magnesium, barium, based on lanthanides such as lanthanum, cerium and gadolinium).

[0075] The autoclave material is preferably organic.

[0076] For example, the thermoplastic material can be selected from: alkyl carboxylic acids, alkyl carboxylates (especially barium or calcium salts of alkyl carboxylates), liquid crystals (such as 4-(trans-4-pentylcyclohexyl)benzonitrile (PCH5)), plastic crystals (especially neopentyl glycol (NPG) or 1-adamantanol, 2-amino-2-(hydroxymethyl)propane-1,3-diol), ammonium sulfate salts, and mixtures thereof.

[0077] The autoclave material is preferably a plastic, in particular neopentyl glycol or 1-adamantanol, more in particular neopentyl glycol.

[0078] The thermal mass material in particulate form is present in an amount ranging from 2% to 98% by weight relative to the total weight of the fluid.

[0079] The thermal mass material in particulate form is present in a content preferably greater than or equal to 10% by weight, preferably greater than or equal to 15% by weight, preferably greater than or equal to 20% by weight, preferably greater than or equal to 25% by weight, preferably greater than or equal to 30% by weight, preferably greater than or equal to 35% by weight, preferably greater than or equal to 40% by weight, preferably greater than or equal to 45% by weight, preferably greater than or equal to 50% by weight, relative to the total weight of the fluid.

[0080] The thermal mass material in particulate form is preferably present in a content of less than or equal to 90 wt %, preferably less than or equal to 85 wt %, more preferably less than or equal to 70 wt %, even more preferably less than or equal to 60 wt %, relative to the total weight of the fluid.

[0081] The thermal mass material in particulate form is preferably present in a content ranging from 2 wt % to 90 wt %, 2 wt % to 85 wt %, 2 wt % to 70 wt %, 2 wt % to 60 wt % relative to the total weight of the fluid.

[0082] The thermal mass material in particulate form is preferably present in a content varying from 10% to 90% by weight, preferably from 20% to 80% by weight, more preferably from 30% to 70% by weight, still more preferably from 40% to 60% by weight, relative to the total weight of the fluid.

[0083] The thermal mass material in particulate form is preferably present in an amount of 40 to 95 wt %, more preferably 50 to 90 wt %, relative to the total weight of the fluid.

[0084] The particles of the thermal mass material preferably have an average size in the range of 0.1 to 1000 μm, preferably in the range of 1 to 500 μm.

[0085] Within the meaning of the present invention, "particle size" corresponds to the largest dimension measurable between two diametrically opposite points of a single particle.

[0086] The size can be determined, for example, by transmission electron microscopy or from measurements of the specific surface area by the BET method or using a laser diffraction analyser.

[0087] The average size of the particles is preferably a number average size.

[0088] The fluid may be a heat transfer fluid, preferably a liquid at a temperature of 23°C.

[0089] The fluid is preferably selected from alcohols, oils, polar solvents and mixtures thereof.

[0090] For example, the fluid may be selected from water, alkanes, olefins, alcohols, ethers, esters, amines, amides, sulfoxides, fluoroalkanes, perfluoroalkanes, chloroalkanes, siloxanes.

[0091] The fluid may preferably be selected from the group consisting of hexane, ethanol, toluene, acetone, di-n-propyl ether, tetrahydrofuran, 1-butanol, butanamide, pyrrolidine, dimethyl sulfoxide, 1-fluoropentane, water and polydimethylsiloxane and mixtures thereof.

[0092] The fluid is preferably selected from alcohols, oils, polar solvents and mixtures thereof, and the thermal mass material is a pressure thermal mass material, in particular selected from alkyl carboxylic acids, alkyl carboxylates (in particular barium or calcium salts of alkyl carboxylates), liquid crystals (for example 4-(trans-4-pentylcyclohexyl)benzonitrile (PCH5)), plastic crystals (in particular neopentyl glycol (NPG) or 1-adamantanol, 2-amino-2-(hydroxymethyl)propane-1,3-diol), ammonium sulfate salts and mixtures thereof.

[0093] The fluid is preferably selected from the group consisting of alcohols, oils, polar solvents and mixtures thereof, and the thermal mass material is a pressure thermal mass material, in particular neopentyl glycol or 1-adamantanol, more in particular neopentyl glycol.

[0094] Composition

[0095] As stated above, the composition comprises at least one fluid as defined above.

[0096] The composition according to the invention may also contain one or more additives selected from the group consisting of surfactants, antioxidants, dispersants, friction modifiers, antifreeze agents, demulsifiers, antibacterial agents, olfactory tracers and mixtures thereof.

[0097] The additives may be present in the composition according to the invention in a content ranging from 0.05 to 5% by weight, preferably ranging from 0.1% to 3% by weight, relative to the total weight of the composition.

[0098] use

[0099] The invention also relates to the use of a fluid as defined above as a heat transfer fluid, in particular in a thermodynamic system involving heat transfer.

[0100] The fluid is preferably used as a heat transfer fluid in thermodynamic systems or applications involving heat transfer.

[0101] The fluid is preferably used as a heat transfer fluid in thermal systems, cryogenic applications or in systems for converting mechanical energy into pressure.

[0102] The invention also relates to the use of a composition as described above for transferring heat.

[0103] The composition is preferably used to transfer heat in thermodynamic systems or applications involving heat transfer as described above.

[0104] The thermal system may be a refrigeration, air conditioning or heating system, preferably a refrigeration or heating system.

[0105] The refrigeration system may be a refrigeration system (including freezing) used in the residential and / or industrial sectors, for example in the agri-food sector, in particular for refrigerating food, in the medical sector, in particular for refrigerating pharmaceutical compositions, or in the electronics sector, designed for battery cooling systems for electric vehicles, industrial cooling systems, in particular for gas separation in hydrogen stations and refineries, for example cooling units for separation of olefins at the outlet of a steam cracker.

[0106] The refrigeration system is preferably an industrial cooling system, in particular a cooling unit for hydrogen stations and gas separation units in refineries.

[0107] The air conditioning system may be a residential or industrial air conditioning system or an air conditioning system designed for transport, for example in automobiles, heavy goods vehicles or in the aviation sector.

[0108] The heating system is in particular a heat pump, in particular for residential or industrial heating and reheating, such as air, de-icing, oil or water reheating.

[0109] Cryogenic applications may be, for example, natural gas liquefaction or hydrogen liquefaction.

[0110] The fluid is preferably used as a heat transfer fluid in a refrigeration, air conditioning or heating system, preferably in a refrigeration or heating system, more preferably in a refrigeration system, in particular for use in batteries of vehicles, such as light or heavy goods.

[0111] The composition is preferably used for transferring heat in refrigeration, air conditioning or heating systems, more preferably for transferring heat in refrigeration or heating systems, more preferably for transferring heat in refrigeration systems, in particular for batteries of vehicles (eg light or heavy cargo).

[0112] Thermal System

[0113] The present invention also relates to a thermal system comprising at least one composition as described above or a fluid as defined above, at least one heat source heat exchanger, at least one cold source heat exchanger and at least one device for applying at least one physical field capable of inducing a heat flux greater than or equal to 100 J.K in the thermal mass material of the composition or the fluid. - 1 .kg -1 The absolute entropy change ΔS.

[0114] The device preferably applies at least one electric field, magnetic field and / or mechanical stress, such as pressure stress, more preferably an electric field and / or mechanical stress.

[0115] Still more preferably, the device applies at least one electric field and / or a pressure stress, in particular a pressure stress.

[0116] The device preferably applies a physical field, in particular a pressure stress.

[0117] The external physical field is preferably applied at a temperature ranging from 231K to 420K, preferably ranging from 233K to 400K, and more preferably from 273K to 320K.

[0118] By way of example, the means for applying at least one physical field may be selected from an electromagnet, an electric field generator and / or a hydraulic actuator (eg a hydraulic actuator).

[0119] The thermal system may also comprise at least one system, in particular a pump, capable of circulating a composition as described above or a fluid as described above between at least the hot source heat exchanger and at least the cold source heat exchanger.

[0120] The thermal system is preferably a thermal system as defined above.

[0121] The thermal system is preferably selected from a refrigeration system, an air conditioning system or a heating system (such as a heat pump).

[0122] The thermal system is preferably a refrigeration system, preferably a vehicle (eg, light or heavy cargo) battery cooling system.

[0123] The thermal system is preferably an air conditioning system.

[0124] The thermal system is preferably a heating system.

[0125] method

[0126] Another object of the present invention is a heat transfer method, which comprises at least circulating a composition as defined above or a fluid as defined above between at least one heat source heat exchanger and at least one heat sink heat exchanger, and applying at least one physical field to induce a heat transfer greater than or equal to 100 J.K in the thermal mass material of said composition or said fluid. -1 .kg -1 The absolute entropy change ΔS.

[0127] The circulation of the composition or fluid is preferably achieved by at least one circulation pump.

[0128] The external physical field may preferably be at least one of an electric field, a magnetic field and / or a mechanical stress, such as a pressure stress, more preferably an electric field and / or a mechanical stress.

[0129] More preferably, the external physical field is an electric field and / or a pressure stress, in particular a pressure stress.

[0130] The external physical field is preferably applied at a temperature in the range of 231 K to 420 K, preferably in the range of 233 K to 400 K, more preferably in the range of 273 K to 320 K.

[0131] According to the invention, in particular a physical field is applied so that the thermal mass material is preferably at least temporarily exposed to an interaction with said physical field, preferably with a magnetic field, an electric field and / or a mechanical stress, in particular a pressure stress.

[0132] The method according to the invention is preferably a heat transfer method within a thermal system as described above, which thermal system is preferably selected from a refrigeration system, an air conditioning system or a heating system (such as a heat pump).

Claims

1. A thermal fluid comprising solid particles of at least one thermal mass material having a thermal conductivity greater than or equal to 100 J.K under the action of at least one external physical field. -1 .kg -1 The absolute entropy change ΔS of the fluid varies between 2 wt % and 98 wt % relative to the total weight of the fluid.

2. The fluid according to claim 1, characterized in that The external physical field is selected from electric field, magnetic field and / or mechanical stress, preferably electric field and / or pressure stress.

3. The fluid according to claim 1 or 2, characterized in that The external physical field is pressure stress.

4. Fluid according to any one of the preceding claims, characterized in that The thermal mass material in particulate form is present in a content varying from 10% to 90% by weight, preferably from 20% to 80% by weight, more preferably from 30% to 70% by weight, even more preferably from 40% to 60% by weight, relative to the total weight of the fluid.

5. Fluid according to any one of the preceding claims, characterized in that The particles of the thermal mass material have an average size in the range of 0.1 μm to 1000 μm, preferably in the range of 1 μm to 500 μm.

6. Fluid according to any one of the preceding claims, characterized in that The material is a pressure-controlled thermal mass material.

7. A fluid according to any one of the preceding claims, characterised in that The fluid is selected from the group consisting of water, alkanes, olefins, alcohols, ethers, esters, amines, amides, sulfoxides, fluoroalkanes, perfluoroalkanes, chloroalkanes, siloxanes, and mixtures thereof.

8. Fluid according to the preceding claim, characterized in that The fluid is selected from the group consisting of hexane, ethanol, toluene, acetone, di-n-propyl ether, tetrahydrofuran, 1-butanol, butanamide, pyrrolidine, dimethyl sulfoxide, 1-fluoropentane, water, polydimethylsiloxane and mixtures thereof.

9. Use of a fluid as defined in any one of the preceding claims as a heat transfer fluid, preferably in a thermodynamic system or application involving heat transfer.

10. Composition comprising at least one thermal fluid as defined in any one of claims 1 to 8 and possibly one or more additives selected from surfactants, antioxidants, dispersants, friction modifiers, antifreeze agents, demulsifiers, antibacterial agents, olfactory tracers and mixtures thereof.

11. Use of a composition as defined in claim 10 for transferring heat, preferably in thermodynamic systems or applications involving heat transfer, more preferably in thermal systems, cryogenic applications or systems for converting mechanical energy into pressure.

12. The use according to claim 11, characterized in that The thermal system is a refrigeration, air conditioning or heating system, preferably a refrigeration or heating system.

13. The use according to claim 12, characterized in that The refrigeration system is a system in the agri-food sector, in particular a system in the agri-food sector for refrigerating foods, a system in the medical sector, in particular a system in the medical sector for refrigerating pharmaceutical compositions, or a system in the electronics sector, designed for battery cooling systems of electric vehicles, industrial cooling systems, in particular cooling units for gas separation units in hydrogen stations and refineries, preferably for battery cooling systems of electric vehicles.

14. A thermal system comprising at least one composition as defined in claim 10 or a fluid as defined in any one of claims 1 to 8, at least one heat source heat exchanger, at least one heat sink heat exchanger and at least one device for applying at least one physical field capable of inducing a thermal conductivity greater than or equal to 100 J.K in the thermal mass material of the composition. -1 .kg -1 The absolute entropy change ΔS.

15. The thermal system according to claim 14, characterized in that The device is a device for applying at least one electric field, a magnetic field and / or a mechanical stress, preferably a pressure stress.

16. The system according to claim 14 or 15, characterized in that The system is selected from a refrigeration system, an air conditioning system or a heating system, and the refrigeration system is preferably a vehicle battery cooling system.

17. A heat transfer method comprising circulating at least a composition as defined in claim 10 or a fluid as defined in any one of claims 1 to 8 between at least one hot source heat exchanger and at least one cold source heat exchanger, and applying at least one physical field to induce a heat transfer greater than or equal to 100 J.K in a thermal mass material of the composition or the fluid. -1 .kg -1 The absolute entropy change ΔS of the physical field is preferably an electric field, a magnetic field and / or a mechanical stress, and the mechanical stress is especially a pressure stress.