COOLING SYSTEM, AIR-CONDITIONING SYSTEM, MOTOR ASSEMBLY AND ASSOCIATED METHODS

Abstract

The invention relates to a cooling system (1) comprising at least: a Stirling heat pump (2) designed to cool an inlet gas (Ge) down to a cryogenic temperature so as to form a cryogenic liquid (L), a primary electric motor (3), intended to put said Stirling heat pump (2) into operation, a primary pump (4) intended to cause said cryogenic liquid (L) to circulate under pressure, and a cooling means (5) intended to cool said primary electric motor (3) with the aid of the cryogenic liquid (L) output by said primary pump (4). The invention is particularly suitable for the production of a cryogenic liquid and the applications thereof.

Description

TECHNICAL FIELD

The present invention relates to the general field of cooling an initially gaseous component down to liquefaction, more precisely to a very low temperature, and in particular a cryogenic temperature.

The invention therefore relates to a cooling system.

The invention further relates to an air-conditioning system, a motor assembly, and associated adaptation method, cooling method and oxycombustion method.

PRIOR ART

Traditionally, the regulated use, transportation and storage of a gaseous component requires carrying out a concentration of this gaseous component, for example by means of a compressor. The concentration operation may also be carried out by liquefaction of the initially gaseous component.

To carry out the liquefaction of a gaseous component, it is hence known to implement cooling systems and compression systems.

These systems dedicated to the liquefaction of a gas, although generally satisfactory in their use, have nevertheless some disadvantages.

Therefore, the known cooling systems dedicated to gas liquefaction suffer from a high energy cost, a poor efficiency at best, a complex implementation and a significant dimensioning with regard to the relatively small quantity of liquefied gas produced per time unit.

The known compression systems, in particular those dedicated to gas liquefaction, also suffer from a high energy cost, especially as they further suffer from significant losses of calories due to the gas compression and the frictions inherent to the movement of their compression member, for example a piston in the case of a reciprocating compressor. Such a configuration limits in practice the compression rate of each stage, in particular when it is necessary to reach high pressures. Compressors may therefore need to be cooled at each of their stages, which consumes even more energy. Finally, the known compression systems suffer from significant safety risks associated with the storage of compressed gas, and are generally not adapted, alone, to the liquefaction of certain gases, in particular the liquefaction of the gaseous components of air.

Therefore, even if gas liquefaction systems are known and implementable as such, the above-mentioned drawbacks show that they are not adapted to a simple, efficient and completely safe implementation of a gas concentration and a fortiori a gas liquefaction.

Eventually, the known gas liquefaction systems, in particular of the cooling or compression liquefaction type, are particularly expensive, energy-consuming and bulky, and present a high risk in terms of safety of goods and people. They are difficult to use outside an industrial installation that is not very modulable and relatively inefficient.

DISCLOSURE OF THE INVENTION

The objects assigned to the present invention therefore aim to remedy the different drawbacks listed hereinabove, and to propose a new cooling system that, while being particularly efficient, is particularly simple to implement, inexpensive and compact.

Another object of the invention aims to propose a new cooling system whose operation is particularly easy to adapt to different uses.

Another object of the invention aims to propose a new cooling system of robust design, which is easy to implement and of excellent energy efficiency.

Another object of the invention aims to propose a new cooling system that is both reliable and economically competitive.

Another object of the invention aims to propose a new cooling system of reduced maintenance cost.

Another object of the invention aims to propose a new cooling system that is particularly wear-resistant and of substantially constant efficiency over time, even if subjected to prolonged and/or successive uses.

Another object of the invention aims to propose a new cooling system having an optimized throughput, thus allowing for the most accurate sizing according to its use.

Another object of the invention aims to propose a new cooling system that is particularly efficient, compact and easily adaptable to a use at different scales.

Another object of the invention aims to propose a new cooling system that is particularly useful in the field of motor vehicles, especially with regard to fuel efficiency and pollution control.

Another object of the invention aims to propose a new cooling system that operates in optimum safety conditions.

Another object of the invention aims to propose a new cooling system that has lithe or no environmental impact and an excellent carbon footprint.

Another object of the invention aims to propose a new air-conditioning system having in particular a great energy efficiency as well as an excellent air-conditioning capacity.

Another object of the invention aims to propose a new motor assembly that is particularly environment-friendly, easy to implement and highly energy efficient.

Another object of the invention aims to propose a new easy-to-implement method for adapting an internal combustion engine making it possible to improve the overall performance of the engine, particularly as regards energy efficiency and emission control.

Another object of the invention aims to propose a new cooling method that is particularly energy-efficient, easy to implement and to adapt to a wide range of applications.

Another object of the invention aims to propose a new oxycombustion method that is particularly efficient, controlled, very low-polluting, and of excellent overall energy efficiency.

The objects assigned to the invention are achieved by means of a cooling system comprising at least:

• • a Stirling heat pump designed to cool an inlet gas down to a cryogenic temperature in order to form a cryogenic liquid,
  • a primary electric motor, intended to operate said Stirling heat pump,
  • a primary pump intended to circulate said cryogenic liquid under pressure, and
  • a cooling means, intended to cool said primary electric motor by means of the cryogenic liquid coming from said primary pump.

The objects assigned to the invention are also achieved by means of a high-power air-conditioning system, characterized in that it comprises the cooling system described hereinabove and hereinafter, the cooling energy of the high-power air-conditioning system being provided via the evaporator.

The objects assigned to the invention are also achieved by means of a motor assembly characterized in that it comprises at least:

• • the cooling system as described hereinabove and hereinafter, said cooling system being designed to produce liquefied dioxygen, and
  • an internal combustion engine, downstream from said cooling system and comprising a combustion chamber,the cooling system being connected to said internal combustion engine in order to be able to inject said liquefied dioxygen into said combustion chamber.

The objects assigned to the invention are also achieved by means of a method for adapting an internal combustion engine comprising at least an intake manifold and a combustion chamber, said adaptation method being characterized in that it comprises at least:

• • a step of closing or removing said intake manifold of the engine,
  • an installation step, in which the cooling system as described hereinabove and hereinafter is connected to said internal combustion engine, at said dosed or removed intake manifold, and thus upstream from said combustion chamber, in order to be able to inject into the latter liquefied dioxygen produced by said cooling system.

The objects assigned to the invention are achieved by means of a cooling method comprising at least:

• • a step of cooling an inlet gas by means of at least one Stirling heat pump, in order to form a cryogenic liquid, said Stirling heat pump being powered by a primary electric motor,
  • a pumping step to circulate said cryogenic liquid under pressure, and
  • a cooling step, during which said primary electric motor is cooled by means of the cryogenic liquid coming from said pumping step.

The objects assigned to the invention are also achieved by means of an oxycombustion method comprising the cooling method as described hereinabove, the oxycombustion method further comprising a step of injecting dioxygen liquefied during the cooling method into a combustion chamber of an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will appear in more detail upon reading of the following description, with reference to the appended drawings, given by way of purely illustrative and non-limiting examples, in which:

FIG. 1 is a simplified schematic illustration of the general principle of the cooling system of the invention.

FIG. 2 is a schematic illustration of a particular embodiment of the cooling system of the invention, with helium cooling.

FIG. 3 is a schematic illustration of another particular embodiment of the cooling system of the invention, with a separation device, the whole being integrated in an example of motor assembly of the invention.

FIG. 4 is a schematic illustration of still another particular embodiment of the cooling system of the invention, with water electrolysis and methanation, the whole being integrated in another example of motor assembly of the invention.

FIG. 5 is a schematic illustration of the separation device of FIG. 3.

FIG. 6 is a schematic illustration of an enlarged detail of FIG. 5.

FIG. 7 is a schematic illustration of a part of the separation device of FIG. 3.

FIG. 8 is cross-sectional view along plane B of the separation device of FIG. 7.

FIG. 9 is a detailed schematic illustration of an example of the operating principle of a magnetic separation device according to the invention.

FIG. 10 is a schematic illustration of the engine of FIG. 3.

WAYS TO IMPLEMENT THE INVENTION

As illustrated in the figures, the invention relates, according to a first aspect illustrated in the figures, to a cooling system 1 comprising at least:

• • a Stirling heat pump 2 designed to cool an inlet gas G_e down to a cryogenic temperature in order to form a cryogenic liquid L,
  • a primary electric motor 3, intended to operate said Stirling heat pump 2.

Therefore, the cooling system 1 of the invention is advantageously designed to cool said inlet gas G_e until the latter liquefies and, more precisely, in such a way that it reaches a cryogenic temperature (also called cryotemperature) to form said cryogenic liquid L. Of course, said inlet gas G_e is preferably formed of at least one component able to reach in liquid form a cryogenic, i.e. rather low, temperature. Said cryogenic liquid L, and references to cryogenics in general, preferably relate to temperatures lower than −50° C., more preferentially −100° C., even more preferentially −150° C. or also −153,15° C. (i.e. 120 K). In other words, said cryogenic temperature is advantageously lower than −50° C., more preferentially −100° C., even more preferentially −150° C. or even more preferentially −153.15° C. (i.e. 120 K). For example, the cryogenic temperature, to which the cryogenic liquid L is thus advantageously brought thanks to said Stirling heat pump 2, is between −150° C. and −270° C., more preferentially between −170 and −250° C., and more preferentially between −196 and −210° C.

Said Stirling heat pump 2 is preferentially a refrigerating machine, and thus advantageously designed to generate cold (sometimes called “Stirling cold”) according to the Stirling cycle but in the reverse direction of operation of a Stirling engine, since the Stirling cycle is reversible. Preferentially, said Stirling heat pump 2 thus requires, in order to generate cold, a mechanical drive provided by said primary electric motor 3. Said Stirling heat pump 2 is thus advantageously designed in such a way as, alone or in combination with possible other cooling devices, to cool said inlet gas G_e, at least until liquefaction thereof, and preferably before the solidification thereof, and more precisely down to said cryogenic temperature.

The invention also relates as such, according to a second aspect illustrated in the figures, to a cooling method comprising at least one step of cooling an inlet gas G_e by means of at least one Stirling heat pump 2, in order to form a cryogenic liquid L, said Stirling heat pump 2 being powered by a primary electric motor 3. The cooling method is of course preferentially implemented by means of the cooling system 1 mentioned hereinabove and described in more detail hereinafter. Therefore, preferentially, the following and preceding description of the cooling system 1 thus also applies to the cooling method of the invention, and vice versa.

According to the invention, the cooling system 1 further comprises at least:

• • a primary pump 4 intended to circulate said cryogenic liquid L under pressure, and
  • a cooling means 5, intended to cool said primary electric motor 3 by means of the cryogenic liquid L coming from said primary pump 4.

According to the invention, the cooling method further comprises:

• • a pumping step to circulate said cryogenic liquid L under pressure, and
  • a cooling step, during which said primary electric motor 3 is cooled by means of the cryogenic liquid L coming from said pumping step.

Naturally, said pumping step is preferably implemented by means of said primary pump 4. Of course, said cooling step is preferentially implemented by means of said cooling means 5, which may for example comprise a heat exchanger (not illustrated) enveloping the primary electric motor 3. Said cooling means 5 further advantageously comprises a recirculation means, for example a pipe, designed to collect the cryogenic liquid L at an outlet of the Stirling heat pump 2 and to inject it into said heat exchanger. Said primary pump 4 is preferably a high-pressure pump, capable of pressurizing said cryogenic liquid L at a pressure higher than 40 bars, preferably higher than 70 bars, more advantageously higher than 100 bars, and for example between 100 and 3000 bars. Said pumping step is thus advantageously a high-pressure pumping step, to bring the cryogenic liquid L to one of the over-mentioned pressure ranges. Optionally, the cooling means 5 is designed to also cool said Stirling heat pump 2 itself by means of said cryogenic liquid L coming from said primary pump 4, accelerating that way the condensation of the cryogenic liquid L within said Stirling heat pump 2 and allowing the latter to minimize the losses (for example, by heating).

One of the advantages of the cooling configuration established by the invention is that the cryogenic liquids often have a very low viscosity, that of liquefied air (forming for example said cryogenic liquid L) being for example about 20 times lower than the viscosity of water in the liquid state. Therefore, it is possible, thanks to the cooling system 1 and to the cooling method of the invention, to easily pressurize said cryogenic liquid L with said primary pump 4, and that at a controlled energy cost because not only of the low viscosity of the cryogenic liquids implemented, but also of the operating temperatures of the primary pump 4, which are advantageously very low and allow the implementation of said primary pump 4 under conditions at the limits of superconductivity, thanks to the cooling of said primary pump 4 itself by said cryogenic liquid L.

Another advantage of the cooling configuration established by the invention is that the pressurization (preferably at a high pressure) of the cryogenic liquid L, which can thus be carried out almost without loss (of electrical energy in particular) by said primary pump 4, makes is possible to maximize the efficiency of use of said cryogenic liquid L in a wide variety of applications. One of the advantages of this pressurization of the cryogenic liquid L is that it allows the latter to cool rapidly enough said primary electric motor 3.

Said primary pump 4 comprises for example a pumping means that can be in particular of the centrifugal, volumetric or vacuum type. In a particularly advantageous manner, the primary pump 4 comprises a secondary electric motor (not illustrated), and the cooling system 1 is designed to cool said secondary electric motor by means of the cryogenic liquid L coming from said Stirling heat pump 2. Thus, preferentially during the cooling step, the cryogenic liquid L coming from said Stirling heat pump 2 cools said secondary electric motor.

According to this configuration, within the cooling system 1, the cryogenic liquid L advantageously allows operating the primary electric motor 3, and preferentially also the secondary electric motor, at cryogenic temperatures. Said electric motor(s) thus advantageously operating in conditions close to superconductivity because of their low operating temperature, this configuration reduces significantly the losses in the magnetic circuit (called “iron” losses) and the losses by Joule effect (called “copper” losses, due to the electrical resistance) of the electric motor(s) 3. Thus, from the energy point of view, the cooling system 1 operates almost without losses other than friction losses, which are otherwise very low within the primary pump 4 and even within the Stirling heat pump 2 when said cryogenic liquid L has a low viscosity. The cooling system 1 and the cooling method can thus be implemented with a minimum of electrical energy, without substantial loss of the latter.

Said primary electric motor 3 and secondary electric motor are preferentially distinct from each other, to allow a better control of the cooling system and the cooling method, but, as an alternative, they may be formed by a same, single electric motor, which performs the two functions of putting said Stirling heat pump 2 into operation and putting said primary pump 4, or more exactly its pumping means, into operation.

According to a particular embodiment of the invention, the cooling system 1 also comprises a device for generating electrical energy from a renewable energy source (not illustrated), said primary electric motor 3 and/or said primary pump 4 being designed to be powered (thus with electrical energy) by said energy generating device. Said energy generating device is for example of the intermittent production type, and can in particular comprise one or several wind turbines, or also one or several solar panels (photovoltaic in particular). Thus, according to this particular embodiment, the cooling method comprises a step of generating electrical energy from a renewable energy source, for example intermittent, such as a wind or solar energy source, to power (thus with electrical energy) said primary electric motor 3 and/or to allow said pumping step. Naturally, said energy generation step is preferably carried out by means of said energy generating device. Such a configuration is particularly advantageous because it represents an optimized carbon footprint, a low overall heating, and therefore an optimized environmental impact, i.e. a reduced or even almost zero or zero impact.

In a particularly advantageous manner, the cooling system 1 further comprises an evaporator 6 intended to evaporate at least part of said pressurized cryogenic liquid L coming from said primary electric motor 3, in order to form an outlet gas G_s and to collect cooling energy. Said evaporator 6 may be formed of one unit or a plurality of units, each unit advantageously forming a specific heat exchanger. Said evaporator 6 can be considered as being an overall heat exchanger, one of the main functions of which is to heat said cryogenic liquid L to evaporate it as said outlet gas G_s. Said evaporator 6 may also be designed to transfer cooling energy from said outlet gas G_s (that remains relatively cold in the evaporator 6, for example about −10 to −120° C.) to another component, or in other words, to transfer heat from this other component to said outlet gas G_s.

According to some particular embodiments, examples of which are illustrated in FIGS. 1 to 4, said evaporator 6 comprises at least one primary heat exchanger 7 intended to collect, on the one hand, said inlet gas G_e to cool it before it enters said Stirling heat pump 2, and on the other hand, at least part of said cryogenic liquid L, coming from said primary electric motor 3, to heat it. Advantageously, said evaporator 6 further comprises at least one secondary heat exchanger 8 intended to heat said outlet gas G_s or at least part of said cryogenic liquid L coming from said primary heat exchanger 7 by means of a heat source Q.

According to the embodiment illustrated in FIG. 1, the cooling system 1 comprises a module 9 for supplying said heat source Q. In a particularly advantageous manner, said supply module 9 is formed by a solar energy production device 10, a system 51 for recovering combustion heat, for example from an internal combustion engine 50, or a system for recovering waste heat from the cooling system 1 or from another system.

According to an embodiment illustrated in FIG. 2, the cooling system 1 comprises a helium liquefaction device 30, which comprises at least:

• • a heat exchanger 31 intended to collect, on the one hand, gaseous helium He to cool it to a cryotemperature, for example 120 K or less (or any other already mentioned cryogenic temperature), and on the other hand, the pressurized cryogenic liquid L coming from the primary electric motor 3 to heat it,
  • an isenthalpic expansion module 32, intended to carry out the isenthalpic expansion of the cooled gaseous helium He coming from the heat exchanger 31, in order to liquefy said gaseous helium He.

In a particularly advantageous manner, said heat exchanger 31 is thus part of said evaporator 6, and may be formed for example by said primary heat exchanger 7 or said secondary heat exchanger 8, or also be a distinct unit. In other words, said evaporator 6 comprises said heat exchanger 31.

Preferably, said helium liquefaction device 30 further comprises at least one or more among:

• • a circuit 33 for cooling a magnetic element 34, such as a medical imaging magnet, using liquefied helium He coming from said isenthalpic expansion module, in such a way that the liquefied helium He be heated enough to be vaporized into gaseous helium He,
  • a secondary compressor 36, intended to compress the gaseous helium He coming from said cooling circuit 33 and to send it to said heat exchanger 31, and
  • a secondary turbine 35, positioned upstream from said isenthalpic expansion module 32 and intended to recover mechanical energy from the cooled gaseous helium He coming from the heat exchanger 31, said secondary turbine 35 powering (at least in part) said secondary compressor 36 (with mechanical energy, directly, or with electrical energy, indirectly, for example via an electrical generating unit).

According to the embodiments illustrated in FIGS. 1 to 4, the cooling system 1 comprises a mechanical energy recovery device 12 to recover the mechanical energy produced by a displacement of said outlet gas G_s. Preferably, the cooling method thus comprises, downstream from said cooling step, a step of recovering the mechanical energy produced by a displacement of said outlet gas G_s. Preferably, said displacement of the outlet gas G_s is caused by the passage of at least part of said cryogenic liquid L to the gaseous state as said outlet gas G_s and/or by a heating and/or an expansion of said second outlet gas component G_s. The displacement of said outlet gas G_s is thus advantageously the source of a mechanical work exploited by said mechanical energy recovery device 12.

Such a configuration makes it possible to obtain a particularly favourable energy balance, i.e. with little waste and losses and maximum energy efficiency. For example, said primary pump 4 is at least partly operated by means of said mechanical energy recovery device 12. Therefore, according to the latter example, said pumping step is at least partly carried out by means of the energy recovered during the mechanical energy recovery step.

According to the embodiment illustrated in FIG. 4, said mechanical energy recovery device 12 comprises at least one electrical generator 13. Said mechanical energy recovery device 12 further comprises for example a primary turbine 14, connected to said electrical generator 13, said primary turbine 14 being rotated by said outlet gas G_s. As an alternative, the mechanical energy recovered by said mechanical energy recovery device 12 is reused in a mechanical form. Said mechanical energy recovery device 12, and more precisely said electrical generator 13, is thus advantageously designed to produce produced electrical energy E_ep from the recovered mechanical energy.

Advantageously, the cooling system 1 comprises, upstream from said Stirling heat pump 2, a primary compressor 15 designed to compress said inlet gas G_e, as illustrated in FIGS. 1 to 4. This compressor 35 advantageously allows facilitating the entry of the inlet gas G_e, for example air, into the cooling system 1, in order to produce said cryogenic liquid L. Preferentially, said primary compressor 15 is at least partly operated by means of said mechanical energy recovery device 12, for example by transmission of mechanical and/or electrical energy E_m/e. Thus, advantageously, the cooling method comprises, upstream from said cooling step, a compression step during which said inlet gas G_e is compressed, said compression step being more preferentially at least partly carried out by means of the energy recovered during said mechanical energy recovery step. The energy balance and overall efficiency of the cooling system 1 are hence further improved.

According to the embodiment illustrated in FIG. 4, the cooling system further comprises a module 16 for electrolysing water H₂O into dihydrogen H₂ and dioxygen O₂, powered at least by said electric generator 13. Therefore, said electric generator 13 provides the produced electrical energy E_ep to the electrolyse module 16, advantageously continuously, which allows saving significant quantities of energy because it is no longer necessary to power said electrolyse module 16 completely independently. Such a configuration is particularly advantageous because water electrolyse is very expensive in terms of electrical energy.

According to the embodiment illustrated in FIG. 4, the cooling system 1 advantageously comprises a heat exchanger module 17 designed to:

cool at least down to liquefaction the dioxygen O₂ coming from the electrolyse module 16 in order to form liquefied dioxygen O₂, and

• • heat the outlet gas G_s coming from the mechanical energy recovery device 12.

Still according to the embodiment of FIG. 4, the cooling system 1 also comprises a methane reforming unit 18, designed to react carbon dioxide CO₂ with dihydrogen H₂ coming from said water electrolysis module 16 in order to form methane CH₄ and water H₂O. The so-formed methane CH₄ can advantageously be injected into an internal combustion engine 50 as a fuel, whereas the liquefied dioxygen O₂ can be injected into said internal combustion engine 50 as an oxidizer.

The invention also relates as such, according to a third aspect illustrated by the examples in FIGS. 3 and 4, to a motor assembly 60 comprising at least:

• • the cooling system 1 as described hereinabove and optionally hereinafter, said cooling system 1 being designed to produce liquefied dioxygen O₂, and
  • an internal combustion engine 50, downstream from said cooling system 1 and comprising a combustion chamber 25.

The motor assembly 60 is of course preferentially implemented by means of the cooling system 1 mentioned hereinabove and described in more detail hereinafter. Therefore, preferentially, the above (and optionally following) description of the cooling system 1 and the cooling method thus also applies to the motor assembly 60 of the invention, and vice versa.

According to this third aspect of the invention, the cooling system 1 is connected to said internal combustion engine 50 in order to be able to inject said liquefied dioxygen O₂ into said combustion chamber 25.

According to the embodiment illustrated in FIG. 3, the liquefied dioxygen O₂ comes from the water electrolyse module 16.

Advantageously, the cooling system 1 is also designed to be able to also inject said methane CH₄ into said combustion chamber 25.

For example, the internal combustion engine 50 is a four-stroke engine, a two-stroke engine, a rotary piston engine (as illustrated), a gas turbine or a Stirling engine. Said internal combustion engine 50 is thus advantageously intended to be supply with an oxidizer and a fuel, wherein either of which may come from the said cooling system 1.

According to a particular embodiment an example of which is illustrated in FIG. 3, compatible in particular with the third aspect of the invention and/or with the first and second aspects alone, said cryogenic liquid L coming from said primary electric motor 3 is formed of at least a first component C₁ and a second component C₂, distinct from each other and in the liquid state.

According to the embodiment illustrated in FIG. 3, the cooling system 1 further comprises a separation device 19 designed to separate by magnetism said first and second components C₁, C₂ in the liquid state, one of said first and second components C₁, C₂ in the liquid state having a paramagnetic character far greater than that of the other of said first and second components C₁, C₂. Therefore, according to this latter embodiment, the cooling method further comprises a step of separating by magnetism said first and second components C₁, C₂ in the liquid state. Of course, said separation step is preferentially implemented by means of said separation device 19.

According to a first example, as that illustrated in FIG. 3, said inlet gas G_e is formed by air, said first component C₁ being mainly formed by dioxygen O₂, whereas said second component C₂ is mostly formed by dinitrogen N₂. Preferably, said second component C₂ thus further comprises argon Ar and/or carbon dioxide CO₂, which are both found in air in a proportion far lower than that of dinitrogen N₂. According to a second example, said inlet gas G_e is mainly formed by natural gas or biomethane (i.e. from an essentially biological methane production process), said first component C₁ being predominantly formed of methane CH₄ whereas said second component C₂, in particular in the liquid state, is formed of the natural gas or biomethane effluents, said effluents being, in the present case, preferentially formed of the liquid fraction of the natural gas or biomethane released as a result of processing of the inlet gas G_e (cooling down to liquefaction) cleared of its main valuable product, i.e. here methane CH₄. Indeed, natural gas and biomethane are usually each formed by a mixture of several chemical species, among which methane CH₄ is normally predominant.

Said separation device 19 preferably further comprises an induction pump 20, for example single-phase or three-phase, designed to expel from the separation device 19 said most paramagnetic component, among said first and second components C₁, C₂, preferably while pressurizing it. Advantageously, said separation device 19 comprises a magnetic trap 21 designed to emit a magnetic field 100 in order to retain the most paramagnetic component, among said first and second components C₁, C₂, substantially within a trap portion 22 of said separation device 19. Advantageously, said separation step thus comprises a magnetic trapping step in which a magnetic field 100 is emitted in such a way as to retain the most paramagnetic component, among said first and second components C₁, C₂, substantially within a trap area 23, which is preferably formed of or surrounded by said trapping portion 22. Naturally, said magnetic trapping step is advantageously implemented by means of said magnetic trap 21. Preferably, said separation device 19 comprises a means 24 for settling said cryogenic liquid L, a portion a least of said settling means 24 forming said trap portion 22. The cooling method thus advantageously comprises a step of settling said cryogenic liquid L, said settling step being preferentially implemented by means of said settling means 24, which comprises for example a settling vessel. Advantageously, said settling and trapping steps are at least partly concomitant. Advantageously, said magnetic trap 21 and said induction pump 20 are used in combination, said induction pump 20 being downstream from the magnetic trap 21 and making it possible to complete the step of separating said first and second components C₁, C₂. According to an example of operation given by way of illustrative and non-limiting example only, to finalize this separation, the first component C₁ in the liquid state (liquid dioxygen O₂ in the case where the inlet gas G_e is air) is sucked into the magnetic trap 21 by the induction pump 20 whose magnetic field, thanks to a phase-shift, generates a magnetic wave that moves along a drainpipe forming an outlet for said first component C₁ in the liquid state, thus attracting the first component C₁ in the liquid state (formed for example of liquid dioxygen O₂) outside the settling means 24, while pressurizing it. The velocity of movement of the first component C₁ in the liquid state is preferentially proportional to the frequency of the current supplying the induction pump 20 and to the Lorentz forces.

As illustrated in FIG. 9, the magnetic trap 21, and more precisely said trap portion 22, advantageously comprises a magnetic network of small magnets 26, which form small three-dimensional cells, and which allow emission of said magnetic field 100. The set of said magnets 17 may form a cube, a cylinder or a cone, and the cells get smaller as they approach the bottom. Such a configuration is similar to a magnetic filter with increasingly fine meshes. In FIG. 9, the indices P+ and P− advantageously represent gradients of partial pressure due to the concentration of the liquid dioxygen O₂ (or more generally the first component C₁) and the liquid dinitrogen N₂ (or more generally of said second component C₂), respectively, within the magnetic trap 21, whereas the horizontal arrows from the signs O₂ and N₂ represent the respective hydraulic velocities of the liquid dioxygen O₂ and the liquid dinitrogen N₂, the waveform on the left representing the velocity distribution of the first and second components C₁, C₂ mixed in the liquid state just before their magnetic separation. Advantageously, under the effect of the magnetic field 100, said liquid dioxygen O₂ (or more generally said first component C₁) gets closer to a first wall 27 of the magnetic trap 21 behind which said magnets 26 are located, whereas the dinitrogen N₂ (or more generally the second component C₂) gets closer to a second wall 28 of the magnetic trap 21 opposite to the first wall 27 and having no magnet, the magnetic field 100 exerting a magnetic force F_m only on the paramagnetic molecules of dioxygen O₂ (or more generally on the most paramagnetic of said first and second components C₁, C₂, preferably said first component C₁), and not on the molecules of dinitrogen N₂. Therefore, according to this alternative with a magnetic separation device 19, the separation step and/or the separation device 19 of the invention use(s) the paramagnetic capacity of the liquid dioxygen O₂ (and more generally said first component C₁ in the liquid state), which is hence retained between magnet poles and/or attracted by a magnetic field 11, to separate it from the dinitrogen N₂ and the argon Ar (and more generally from said second component C₂ in the liquid state). Indeed, the liquid argon Ar and the liquid dinitrogen N₂ being mainly non-magnetic, they are advantageously not retained by the magnetic field 100.

Said induction pump 20 comprises, according to an advantageous example illustrated in FIG. 7, a three-phase wire winding 70 for collecting said first component C₁ in the settling means 6 and, downstream from this winding 70, one or several three-phase coils 71, as illustrated in FIG. 6. Such a configuration preferentially makes it possible both to improve the final separation of said first and second components C₁, C₂, and to pressurize, i.e. to a significant rate, said first liquid component C₁ finally separated from said second liquid component C₂.

This specific configuration with a separation device 19 operating thanks to the magnetism is particularly advantageous, because the operating temperatures of the magnetic separation device 19, and in particular of said magnetic trap 21 and said induction pump 20, are very low (cryotemperatures). Thus, the conductive parts of the separation device 19, in particular in the case of magnets and more particularly electromagnets, are at the limits of the natural superconductivity of copper or aluminium, and electric currents of any magnitude can therefore be used and generate high magnetic forces with little heating and thus little electrical and heat losses.

According to the embodiment illustrated in FIG. 3, the motor assembly 60 is designed in such a way that the cooling system 1 can inject, into said combustion chamber 25, the first component C₁ in the liquid state coming from the separation device 19, said first component C₁ in the liquid state advantageously forming said liquefied dioxygen O₂. Advantageously, said first injected component C₁ is thus intended to serve as an oxidizer in the internal combustion engine 50.

In a particularly advantageous manner, said separation device 19 is thus designed to inject said second component C₂ in the liquid state into said evaporator 6 and not to inject said first component C₁ in the liquid state into the evaporator 6. For example, the motor assembly 60 is designed in such a way that the second component C₂ is formed (mainly) by said liquid dinitrogen N₂ and introduced into the evaporator 6, whereas the first component C₁ is formed by said liquid dioxygen O₂ and directly injected into said internal combustion engine 50, to carry out an oxycombustion, as illustrated in FIG. 3.

Therefore, a specific alternative of the third aspect of the invention relates to a motor assembly 60 comprising:

• • the cooling system 1, and
  • an internal combustion engine 50, downstream from said cooling system 1 and comprising a combustion chamber 25,the cooling system 1 being connected to said engine 26 in order to be able to inject said first component C₁ into said combustion chamber 25. The latter is of course preferentially formed by dioxygen O₂.

Advantageously, said engine 50 comprises an exhaust outlet 42 designed to discharge at least one exhaust component C_e in the gaseous state from said combustion chamber 25. Even more advantageously, downstream from said exhaust outlet 42, said evaporator 6 is designed to cool said exhaust component C_e coming from said exhaust outlet 42 and to heat said second component C₂ coming from said separation device 19. Said exhaust outlet 42 thus advantageously forms a part of said combustion heat recovery device 51.

The fuel of the internal combustion engine 50 may be in particular a hydrocarbon, for example methane CH₄, or dihydrogen H₂. When the fuel is a hydrocarbon and in particular methane CH₄, the exhaust component C_e in the gaseous state, which contains the products of combustion of the engine 26, will be mainly formed of water and carbon dioxide CO₂. When the fuel is dihydrogen H₂, the exhaust component C_e in the gaseous state will be mainly or even almost only formed of water. The absence of dinitrogen N₂ in the combustion chamber, thanks to the direct injection of pure liquid (or potentially gaseous) dioxygen O₂ is one of the advantages of the motor assembly 60 of the invention (two specific variants of which are illustrated in FIGS. 3 and 4), in particular as regards the reduction of pollution related to nitrogen oxide, also called “NO_x”. Indeed, the internal combustion engine 50 of the motor assembly 60, in the absence of nitrogen in the combustion chamber 25, produces no or almost no NOx.

Advantageously, the motor assembly 60 comprises a combustion heat recovery device 51, preferably that described hereinabove, to recover the combustion heat of the exhaust component C_e coming from said combustion chamber 25.

Preferably, the motor assembly 60 is designed in such a way that the evaporator 6 cools said exhaust component C_e at least down to liquefaction of a primary portion of the latter, as illustrated in FIGS. 3 and 4. Preferentially, the motor assembly 60 is designed to use said liquefied primary portion in order to liquefy a secondary portion of said exhaust component C_e, said primary and secondary portions being distinct from each other. Said primary portion is advantageously mainly formed of carbon dioxide CO₂, whereas said secondary portion is mainly formed of water, as illustrated in FIGS. 3 and 4. Even more advantageously, said one combustion heat recovery device 51 comprises a reinjection device (not illustrated), designed to sweep said combustion chamber 25 with said primary portion and/or secondary portion (in the liquid, or alternatively gaseous, state) in order to expel said exhaust component C_e from the combustion chamber 25. Such a configuration allows improving the operation of the internal combustion engine 50 by expelling efficiently the exhaust component C_e from the latter. For example, in particular when the fuel is a hydrocarbon, said reinjection device is designed to inject the liquid primary portion formed of carbon dioxide into said combustion chamber 25, to optimize the sweeping of the latter, i.e. to expel all the gases burnt by the combustion and that form the exhaust component C_e in the gaseous state.

The invention also relates as such, according to a fourth aspect, to a method for adapting an internal combustion engine 50 comprising at least an intake manifold and a combustion chamber 25, said adaptation method comprising at least:

• • a step of closing or removing said intake manifold of the engine 26,
  • an installation step, in which the cooling system 1 as described hereinabove is connected to said internal combustion engine 50, at said closed or removed intake manifold, and thus upstream from said combustion chamber 25, in order to be able to inject into the latter liquefied dioxygen O₂ produced by said cooling system 1.

Advantageously, at the end of said installation step, said internal combustion engine 50 and the cooling system 1 form a motor assembly 60 as described hereinabove.

For example, said liquefied dioxygen O₂ may be formed by said first component C₁ coming from the separation device 19, as illustrated in FIG. 3, or by the dioxygen O₂ formed by the water hydrolysis module 16 and liquefied by said heat exchange module 17, or also a combination of both. Of course, the following and preceding description of the cooling system 1, the motor assembly 60 and the cooling method thus also applies to the adaptation method of the invention, and vice versa.

The invention are also relates as such, according to a fifth aspect, to an oxycombustion method comprising the cooling method as described hereinabove, the oxycombustion method further comprising a step of injecting dioxygen O₂ liquefied during the cooling method into a combustion chamber 25 of an internal combustion engine 50. Of course, the following and preceding description of the cooling system 1, the motor assembly 60, the cooling method and even the adaptation method thus also applies to the oxycombustion method of the invention, and vice versa. For example, said inlet gas G_e being formed by air, said first component is mainly formed by dioxygen O₂, and, during said injection step, the first component C₁ is injected into said combustion chamber 25.

For example, as illustrated in FIG. 10, the internal combustion engine 50 has a rotary piston 44 (having the shape of a Reuleaux triangle). The internal combustion engine 50 with a rotary piston 44 of the alternative illustrated in FIG. 10 comprises two opposing spark plugs 39, two also opposing common fuel and oxidizer injections 40, 41, and two also opposing exhaust outlets 42 designed to discharge the exhaust component C_e in the gaseous state, as described hereinabove. Said oxidizer is preferentially formed by liquid dioxygen O₂, formed for example by said first component C₁. The oxycombustion here allows overcoming the recurring problems of low compression of the conventional rotary piston engines, in particular by adapting the speed of rotation of the rotary piston 44.

The cooling system 1 is also adapted for the production of small quantities of said liquefied first component C₁, or, after return of the latter to the gaseous state, for the production of small quantities of said liquefied first component C₁ in the gaseous state but compressed (that is to say at a relatively high pressure).

The invention also relates as such, according to a fifth aspect not illustrated here, to a high-power air-conditioning system comprising the above-described cooling system, the cooling energy of the high-power air-conditioning system being provided via said evaporator 6.

By convention, in a purely indicative and non-limiting manner, the signs (g) and (liq) are used in the figures to indicate the gaseous and liquid states, respectively, of the various components. In the figures, the arrows located on either side of the continuous lines preferably indicate the direction of a flow, for example a flow of He(_g), that is to say a flow of helium He in the gaseous state.

The terms such as first, second, third, fourth, fifth, primary, secondary, tertiary of the present description are preferably used for distinctive purposes only, and not to denote a rank or an ordinal numbering. A second element may, for example, be introduced without necessarily having a first element of the same nature also introduced or even implicitly present.

POSSIBILITY OF INDUSTRIAL APPLICATION

To summarize, the invention is related to the problems of liquefied gas production, pollution control and energy efficiency of the combustion engines, and more generally of energy-saving, the production of a cryogenic liquid with an optimized energy consumption being a possible application.

Claims

1- A cooling system (1) comprising at least: a Stirling heat pump (2) designed to cool an inlet gas (Ge) down to a cryogenic temperature in order to form a cryogenic liquid (L),a primary electric motor (3), intended to operate said Stirling heat pump (2),a primary pump (4) intended to circulate said cryogenic liquid (L) under pressure, anda cooling means (5), intended to cool said primary electric motor (3) by means of the cryogenic liquid (L) coming from said primary pump (4).

2- The cooling system (1) according to claim 1, characterized in that the primary pump (4) comprises a secondary electric motor, the cooling system (1) being designed to cool said secondary electric motor by means of the cryogenic liquid (L) coming from said Stirling heat pump (2).

3- The cooling system (1) according to claim 1, characterized in that it comprises a helium liquefaction device (30), which comprises at least: a heat exchanger (31) intended to collect, on the one hand, gaseous helium to cool it to a cryotemperature, for example 120 K or less, and on the other hand, the pressurized cryogenic liquid (L) coming from the primary electric motor (3) to heat it,an isenthalpic expansion module (32), intended to carry out the isenthalpic expansion of the cooled gaseous helium (He) coming from the heat exchanger (31), in order to liquefy said gaseous helium (He).

4- The cooling system (1) according to claim 3, characterized in that said helium liquefaction device (30) further comprises: a cooling circuit (33) of a magnetic element (34), such as a medical imaging magnet, using liquefied helium (He) coming from said isenthalpic expansion module (32), in such a way that the liquefied helium (He) is heated enough to be vaporized into gaseous helium (He),a secondary compressor (36), intended to compress the gaseous helium (He) coming from said cooling circuit (30) and to send it to said heat exchanger (31), anda secondary turbine (35), positioned upstream from said isenthalpic expansion module (32) and intended to recover mechanical energy from the cooled gaseous helium (He) coming from the heat exchanger (31), said secondary turbine (35) powering said secondary compressor (36).

5- The cooling system (1) according to claim 1, characterized in that it comprises an evaporator (6) intended to evaporate at least part of said pressurized cryogenic liquid (L) coming from said primary electric motor (3), in order to form an outlet gas (Gs) and to collect cooling energy.

6- The cooling system (1) according to claim 5, characterized in that said evaporator (6) comprises at least one primary heat exchanger (7) intended to collect, on the one hand, said inlet gas (Ge) to cool it before it enters said Stirling heat pump (2), and on the other hand, at least part of said cryogenic liquid (L), coming from said primary electric motor (3), to heat it.

7- The cooling system (1) according to claim 6, characterized in that said evaporator (6) further comprises at least one secondary heat exchanger (8) intended to heat said outlet gas (Gs) or at least part of said cryogenic liquid (L) coming from said primary heat exchanger (7) by means of a heat source (Q).

8- The cooling system (1) according to claim 7, characterized in that it comprises a module (9) for supplying said heat source (Q), said supply module (9) being formed by a solar energy production device (10), a system (51) for recovering combustion heat, or a device for recovering waste heat from the cooling system (1) or from another system.

9- The cooling system (1) according to claim 5, characterized in that it comprises a mechanical energy recovery device (12) to recover the mechanical energy produced by a displacement of said outlet gas (Gs).

10- The cooling system (1) according to claim 9, characterized in that it comprises, upstream from said Stirling heat pump (2), a primary compressor (15) designed to compress said inlet gas (Ge), said primary compressor (15) being at least partly operated by means of said mechanical energy recovery device (12).

11- The cooling system (1) according to claim 9, characterized in that said mechanical energy recovery device (34) comprises at least one electrical generator (13), the cooling system (1) further comprising a module (16) for electrolysing water into dihydrogen (H2) and dioxygen (O2), powered by at least said electric generator (13).

12- The cooling system (1) according to claim 11, characterized in that it further comprises a heat exchange module (17) designed to: cool at least down to liquefaction the dioxygen (O2) coming from the electrolyse module (16) in order to form liquefied dioxygen (O2), andheating the outlet gas (Gs) coming from the mechanical energy recovery device (12).

13- The cooling system (1) according to claim 11, characterized in that it also comprises a methane reforming unit (18), designed to react carbon dioxide (CO2) with dihydrogen (H2) coming from said water electrolysis module (16) in order to form methane (CH4) and water (H2O).

14- The cooling system (1) according to claim 1, characterized in that said cryogenic liquid (L) coming from said primary electric motor (3) is formed of at least a first component (C1) and a second component (C2) distinct from each other and in the liquid state, the cooling system (1) further comprising a separation device (19) designed to separate by magnetism said first and second components (C1, C2) in the liquid state, one of said first and second components (C1, C2) in the liquid state having a paramagnetic character far greater than that of the other of said first and second components (C1, C2).

15- The cooling system (1) according to claim 14, characterized in that it comprises an evaporator (6) intended to evaporate at least part of said pressurized cryogenic liquid (L) coming from said primary electric motor (3), in order to form an outlet gas (Gs) and to collect cooling energy, and in that said separation device (19) is designed to inject said second component (C2) in the liquid state into said evaporator (6) and not to inject said first component (C1) in the liquid state into the evaporator (6).

16- The cooling system (1) according claim 14, characterized in that said separation device (19) further comprises an induction pump (20), for example single-phase or three-phase, designed to expel from the separation device (19) said most paramagnetic component, among said first and second components (C1, C2), preferably while pressurizing it.

17- The cooling system (1) according to claim 14, characterized in that said separation device (19) comprises a magnetic trap (21) designed to emit a magnetic field (100) in order to retain the most paramagnetic component, among said first and second components (C1, C2), substantially within a trap portion (22) of said separation device (19).

18- The cooling system (1) according to the claim 17, characterized in that said separation device (19) comprises a means (24) for settling said cryogenic liquid (L), a portion a least of said settling means (24) forming said trap portion (22).

19- The cooling system (1) according to claim 14, characterized in that said inlet gas (Ge) is formed by air, said first component (C1) being mainly formed by dioxygen (O2), whereas said second component (C2) is mostly formed by dinitrogen (N2).

20- The cooling system (1) according to claim 14, characterized in that it is connected to a internal combustion engine (50) comprising a combustion chamber (25), the cooling system (1) being designed to inject, into said combustion chamber (25), the first component (C1) coming from the separation device (19).

21- The cooling system (1) according to the claim 20, characterized in that said first injected component (C1) is intended to serve as an oxidizer in the internal combustion engine (50).

22. (canceled)

23- A motor assembly (60) characterized in that it comprises at least: the cooling system (1) according to claim 1, said cooling system (1) being designed to produce liquefied dioxygen (O2), andan internal combustion engine (50), downstream from said cooling system (1) and comprising a combustion chamber (25), the cooling system (1) being connected to said internal combustion engine (50) in order to be able to inject said liquefied dioxygen (O2) into said combustion chamber (25).

24- A motor assembly (60) according to claim 23, characterized in that said cryogenic liquid (L) coming from said primary electric motor (3) is formed of at least a first component (C1) and a second component (C2) distinct from each other and in the liquid state, the cooling system (1) further comprising a separation device (19) designed to separate by magnetism said first and second components (C1, C2) in the liquid state, one of said first and second components (C1, C2) in the liquid state having a paramagnetic character far greater than that of the other of said first and second components (C1, C2), and that he motor assembly is designed in such a way that the cooling system (1) can inject, into said combustion chamber (25), the first component (C1) in the liquid state coming from the separation device (19), said first component (C1) in the liquid state advantageously forming said liquefied dioxygen (O2).

25- The motor assembly (60) according to claim 24, characterized in that said mechanical energy recovery device (34) comprises at least one electrical generator (13), the cooling system (1) further comprising a module (16) for electrolysing water into dihydrogen (H2) and dioxygen (O2), powered by at least said electric generator (13), and in that said liquefied dioxygen (O2) comes from said water electrolyse module (16).

26. (canceled)

27. (canceled)

28- A cooling method comprising at least: a step of cooling an inlet gas (Ge) by means of at least one Stirling heat pump (2), in order to form a cryogenic liquid (L), said Stirling heat pump (2) being powered by a primary electric motor (3),a pumping step to circulate said cryogenic liquid (L) under pressure, anda cooling step, during which said primary electric motor (3) is cooled by means of the cryogenic liquid (L) coming from said pumping step.

29- The cooling method according to claim 28, characterized in that said cryogenic liquid (L) coming from said primary electric motor (3) is formed of at least a first component (C1) and a second component (C2), distinct from each other and in the liquid state, the cooling method further comprising a step of separating by magnetism said first and second components (C1, C2) in the liquid state, one of said first and second components (C1, C2) in the liquid state having a paramagnetic character far greater than that of the other of said first and second components (C1, C2).

30. (canceled)