HK1122610A - Thermal generator having a magnetocaloric material - Google Patents

Description

Thermal generator of magnetocaloric material type

Technical Field

[01] The invention relates to a thermal generator of magnetocaloric material, comprising: at least one fixed support carrying at least two thermal elements of magnetocaloric material; a magnetic member movable relative to the thermal element to subject the thermal element to a change in magnetic field to change its temperature; and a thermal and cold energy recovery means recovering the thermal and cold energy emitted by the thermal elements and comprising at least two circuits of heat-carrying fluid, namely a "hot" circuit and a "cold" circuit, each circuit being connected to at least one heat exchanger and provided with conversion means so that the respective thermal elements are placed alternately in the circuits.

Background

[02] Thermal generators of the magnetocaloric material type make use of the magnetocaloric properties of certain materials, such as gadolinium or certain alloys, which have the property of heating under the action of a magnetic field and cooling to a temperature lower than their initial temperature after the magnetic field has disappeared or has decreased. This magnetocaloric effect is generated in the vicinity of the curie point of the material. The advantage of this new generation of heat generators is to provide a method which is very ecological as it is free from pollution. However, the design of such heat generators and their components for recovering the thermal and cold energy (frigorie) emitted by these materials is extremely important in order to be cost effective and provide good energy efficiency.

[03] The document WO-A-03/050456 gives A first example in which A thermal generator of magnetocaloric material comprises A monolithic annular enclosure defining twelve compartments separated by A spacer element, and each compartment receiving gadolinium in the form of A void. Each compartment is provided with four apertures, wherein an input aperture and an output aperture are connected to a hot circuit and an input aperture and an output aperture are connected to a cold circuit. The two permanent magnets are excited to perform a continuous rotary motion so that they sweep through the different compartments and subject them to different magnetic fields one after the other. The thermal and cold energy emitted by the gadolinium in the different compartments is directed to heat exchangers through hot and cold circuits in which a heat-carrying fluid flows, and the hot and cold circuits are connected to the heat exchangers in succession through rotary joints, the rotation of which is synchronized with the rotation of the magnets. The necessity associated with this synchronous rotation makes the implementation of the device technically difficult and expensive. In addition, the operating principle of the device makes the technical development prospect of the device very limited. In addition, the construction of the device is complex and expensive due to the different pipes, connections and valves required to implement the hot and cold circuits. On the other hand, the energy efficiency of such a generator is still insufficient, which greatly limits its applications. In fact, the heat transfer fluid flowing through the pores of the magnetocaloric material is the same for both the cold circuit and the hot circuit, except that their flow direction is opposite, the thermal inertia thus obtained being very harmful.

[04] The document FR- A-2861454 presents A second example in which A duct passes through the thermal element, said duct being located in proximity to the magnetocaloric material and communicating with the heat transfer fluid circuit through A plate on which the thermal element is mounted. The plate comprises a number of ducts defining a hot circuit and a cold circuit, in which the heat transfer fluid flows, and to which the ducts of the thermal element are directly connected, without tubes and without intermediate connections. The advantage of this construction is that the manufacturing costs of such a generator are significantly reduced and a great flexibility of shape is provided. However, disadvantages are also encountered in connection with a single heat carrier fluid, which flows in the hot element for both the cold circuit and the hot circuit. The thermal efficiency of the method is insufficient.

Disclosure of Invention

[05] The object of the present invention is to overcome these drawbacks and to propose a heat generator that is pollution-free, has very good energy efficiency, is simple and economical in design, low in energy consumption, scalable, flexible, modular and can be used in large-scale industrial installations and for domestic applications.

[06] To this end, the invention relates to a heat generator of the type mentioned in the introduction, characterised in that each thermal element comprises a fluid channel forming at least two distinct collector circuits, "hot" collector circuits, in which the heat carrier fluid of the hot circuit responsible for collecting the thermal energy emitted by the thermal element subjected to a magnetic field flows, and "cold" collector circuits, in which the heat carrier fluid of the cold circuit responsible for collecting the cold energy emitted by the thermal element not subjected to a magnetic field flows, said heat carrier fluid moving alternately in one or the other collector circuit depending on whether the thermal element is subjected to a magnetic field and whether it emits thermal or cold energy.

[07] The thermal element is at least partially made of magnetocaloric material, said magnetocaloric material having at least a shape chosen in the group consisting of: solid blocks, stacks of solid blocks or plates, particle assemblies, void blocks, stacks of void blocks or plates, combinations of these shapes.

[08] Said collector circuits are preferably each formed by a plurality of fluid channels distributed in the thickness of said thermal element to provide a large heat exchange area, said fluid channels having small dimensions, comprised between 0.01mm and 5mm, and preferably equal to 0.15mm, and being suitable to generate a substantially laminar flow of said heat-carrying fluid through said thermal element. The orientation of the fluid channels of the two collector circuits of each thermal element may be parallel or different, for example perpendicular. The fluid channel is formed by at least one formation selected from the group consisting of: perforations, grooves, slits, voids, combinations of these shapes, formed by machining, chemical or ionic or mechanical engraving, shaping, interlayers between blocks or plates, spaces between particles.

[09] In a preferred embodiment of the invention, the fixed support comprises at least one plate provided with: at least two openings forming a cavity to receive the thermal element therein; and at least two rows of ducts forming part of said hot and cold circuits of heat transfer fluid and opening into each cavity through an inlet and an outlet suitable for communicating with the respective fluid channels of the thermal element, that is to say two inlets and two outlets per cavity.

[10] The ducts may be formed by grooves distributed on one or both surfaces of the plate; and an additional side plate covers the one or both surfaces, the side plate being arranged to plug and seal the duct.

[11] The thermal element and the cavity advantageously have complementary engagement shapes, which may be substantially parallelepiped; each side of said cavity comprising an inlet or an outlet of one of said hot and cold circuits of the heat transfer fluid; and each side of the thermal element includes an inlet or an outlet of one of its collector circuits.

[12] In a preferred embodiment, a gap of 0.05 to 15mm, and preferably equal to 1mm, is provided in each side between the cavity and the thermal element, so as to form a heat carrier fluid distribution chamber extending over the thickness of the thermal element; and a sealing mechanism is located in each corner of the cavity.

[13] The heat generator advantageously comprises an even number of thermal elements distributed substantially circularly around the central axis of the support; also, the magnetic member is preferably connected to a driving member that rotates around the central axis.

[14] The magnetic means may comprise a number of magnets corresponding to the number of thermal elements, the magnets being coupled in pairs and located on each side of the thermal elements so that one of the two thermal elements is subjected to a magnetic field. In a preferred embodiment, the thermal elements are arranged adjacent to each other such that pairs of magnets travel from one row of thermal elements to the other without switching off the magnetic field.

[15] The means for recovering heat and cold energy may comprise means for forcing the flow of the heat-carrying fluid, provided in one or both of the heat-carrying fluid circuits. In the first case, two heat transfer fluid circuits, cold and hot, are connected in a closed loop, the hot circuit of the heat transfer fluid connecting the outlet of the cold heat exchanger with the inlet of the hot heat exchanger, and the cold circuit of the heat transfer fluid connecting the outlet of the hot heat exchanger with the inlet of the cold heat exchanger. In the second case, the two heat transfer fluid circuits, cold and hot, are independent and each circuit forms a closed loop. The heat transfer fluids of the cold and hot circuits preferably flow in opposite directions.

[16] The switching means may comprise at least one valve provided on each of the hot and cold circuits of the heat transfer fluid and arranged for connecting in series one or the other of the collector circuits of the thermal element depending on whether the thermal element is subjected to a magnetic field and releases thermal or cold energy.

Drawings

[17] The invention and its advantages will be more clearly apparent in the following description of an embodiment thereof, given as a non-limiting example with reference to the accompanying drawings, in which:

[18] figure 1 is a simplified perspective view of a heat generator according to the invention;

[19] figure 2 is an exploded view of the generator of figure 1;

[20] figure 3 is a perspective view of the plate of the generator of figure 1 without the thermal element;

[21] figure 4 is a perspective view of a thermal element for mounting in the panel of figure 3, and figure 4A is an enlarged view of detail a of figure 4; and

[22] figures 5A and 5B are schematic views showing the heat transfer fluid circuit according to two operating cycles.

Detailed Description

[23] With reference to fig. 1 and 2, a thermal generator 1 of magnetocaloric material according to the invention comprises a fixed support in the form of a plate 2 arranged to carry at least two, and in the example shown eight, thermal elements 3 of magnetocaloric material. The generator further comprises: a magnetic member 4 movable with respect to the thermal elements 3 so as to subject the latter to a variation in magnetic field to change their temperature; and a thermal and cold energy recovery part 5 that recovers thermal energy (calorie) and cold energy emitted from the heat element 3. The recovery means 5 comprise in particular two separate heat-carrying fluid circuits 51, 52, i.e. a "hot" circuit 51 for recovering thermal energy and a "cold" circuit for recovering cold energy, which are hydraulically sealed from each other, each circuit 51 and 52 being connected to at least one heat exchanger capable of using these thermal and cold energies, for industrial and domestic heating, tempering (temp.), cooling, air conditioning or similar applications.

[24] In the example shown, the thermal elements 3 are located in the cavity 20 of the plate 2 and are distributed substantially circularly around a central axis B. The magnetic means 4 comprise eight permanent magnets 40 distributed in pairs on either side of the plate 2 so as to subject one of the two thermal elements 3 to a magnetic field. These permanent magnets 40 are carried by two frames 41 provided on each side of the plate 2, and said frames 41 are set in rotation by a drive shaft (not shown) connected, directly or through any type of suitable mechanical transmission, to any type of starter, such as a motor, a motor reducer, a stepper motor, a servomotor, a rotary actuator, etc.

[25] The advantage of this configuration of the thermal element 3, which is circular about the axis B, is: a simple way of bringing the magnetic part 4 by continuous rotation in the same direction can be used. Of course, any other configuration may be used. For example, if the thermal elements 3 are distributed in a linear shape, it is chosen to bring the magnetic part 4 by means of alternate translations.

[26] The permanent magnets, which may be solid, calcined or layered, are combined with one or more magnetizable materials which concentrate their magnetic field lines and point in the direction of the heat element 3. Other types of magnets are also possible, such as electromagnets or superconductors. However, permanent magnets have certain advantages in terms of size, simplicity of use and low cost. The permanent magnet 40 is preferably selected to be capable of generating a magnetic field of at least 1 Tesla.

[27] In addition, the thermal elements 3 are arranged adjacent to each other so that the pairs of magnets 40 run from one row of thermal elements 3 to the other without interrupting the magnetic flow. This arrangement has the advantage of greatly limiting the power required to move the magnetic component 4, as it is not required to withstand magnetic forces.

[28] The panel 2 is a plate preferably made of a material that is thermally insulating and non-magnetic. The plate 2 comprises openings forming cavities 20 and having a scarf shape complementary to the thermal element 3 and substantially equal in thickness, so that the thermal element 3 is flush with the surface of the plate 2. Other configurations are possible and it is important that each thermal element 3 is excited by the magnetic field of the permanent magnet 40.

[29] More particularly, with reference to fig. 3, the plate 2 comprises two series of pipes 21, 22 forming the inner part of a hot circuit 51 of heat carrier fluid and of a cold circuit 52 of heat carrier fluid. The ducts 21, 22 of each column open into the cavities 20, on the one hand, by providing inlet and outlet holes for the fluid communicating with the thermal elements 3, i.e. two inlet and two outlet holes per cavity 20, and the ducts 21, 22 of each column open out of the plate 2, on the other hand, by means of inlet and outlet holes provided for connection with the hot circuit 51 of the heat carrier fluid, including in particular the heat exchangers, and the external part of the cold circuit 52 of the heat carrier fluid. In the example shown, these ducts 21, 22 are distributed on both surfaces of the plate 20 and are formed by grooves made, for example, by machining, engraving, moulding or any other suitable technique. In this embodiment, the plate 2 is associated with two sealing means 6 in the form of non-metallic side plates 60, which are provided for each abutting against the plate 2 by means of a gasket 61 in the form of a membrane, thus allowing to close and seal the ducts 21, 22. In the example shown, the side plates 60 and the padding 61 comprise cut-outs 62, 63 arranged in correspondence with the thermal elements 3 and which are assembled on the plate 2, for example by screwing or in any other equivalent way. The side plates 60 and the padding 61 may also be solid. Of course, the ducts 21, 22 may be provided on only a single surface of the plate 2. The plate 2 can also be formed in different ways, for example from two moulded and assembled parts, with the ducts 21, 22 inside. Also, the pad 61 may be replaced with an appropriate glue or the like.

[30] The thermal element 3 is at least partially, and preferably entirely, made of a magnetocaloric material, such as gadolinium (Gd), gadolinium alloys containing, for example, silicon (Si), germanium (Ge), magnesium alloys containing, for example, iron (Fe), magnesium (Mg), phosphorus (P), or any other similar magnetizable material or alloy. The selection between these magnetocaloric materials is made according to the required heating and cooling capacity and the required temperature range. Magnetocaloric materials can generally be in the form of: a solid block, a stack of solid blocks or plates, a combination of particles in powder or particulate form, an apertured block, a stack of apertured blocks or plates, or any other suitable shape, as well as combinations of these shapes. Also, the thermal element 3 may be composed of a combination of different magnetocaloric materials. They may also be made of a thermally conductive material comprising one or more magnetocaloric materials.

[31] These thermal elements 3 are characterized in that: each hot part comprises at least two separate, i.e. hydraulically sealed collector circuits 31, 32 from each other, namely a "hot" collector circuit 31 connected to a hot circuit 21, 51 of the heat transfer fluid and a "cold" collector circuit connected to a cold circuit 22, 52 of the heat transfer fluid, the heat transfer fluid of each circuit moving alternately in one or the other collector circuit 31, 32 depending on whether the hot element 3 is subjected to a magnetic field and whether it emits heat or cold energy.

[32] In the example shown in fig. 4 and 4A, the thermal element 3 is formed by a stack of solid plates 30 made of gadolinium. The plates 30 are square in shape and each comprise three ribs, a central rib 33 and two end ribs 34, which are arranged to define two narrow parallel channels between the plates 30 when they are stacked to form fluid passages 35. The plates 30 are alternately oriented in a vertical direction to form two columns of fluid channels 35, thereby forming two different collector circuits 31, 32. These collector circuits 31, 32 are therefore formed by a plurality of fluid channels 35 distributed in the thickness of the thermal element 3 to provide a very large heat exchange area. The thickness of the plate 30 is of the order of one millimetre and the fluid channels 35 are of the order of a fraction of a millimetre, enabling a laminar flow of the heat transfer fluid passing through the thermal element 3, which in turn favours the efficiency of this heat exchange with a minimum amount of heat transfer fluid. These thermal elements 3 thus constitute effective miniature or micro-heat exchangers which generate thermal and cold energy according to the magnetization/demagnetization alternation and exchange thermal and cold energy with the heat-carrying fluid passing through them. These fluid channels 35 may also be oriented in parallel directions.

[33] Each collecting circuit 31, 32 opens onto opposite sides of the thermal element 3 through a fluid inlet and a fluid outlet which automatically communicate with the inlet and outlet of the heat transfer fluid of the hot circuit 21 and the cold circuit 22 respectively provided in each cavity 20 when the thermal element 3 is mounted in the plate 2. For this purpose, a gap of between 0.05mm and 15mm, preferably equal to 1mm, is provided between the plate 2 and the corresponding sides of the thermal element 3, so as to form some heat carrier fluid distribution chambers extending over the thickness of the thermal element 3. The tightness of the collector circuits 31, 32 is ensured on the one hand between the distribution chambers by means of gaskets (not shown) provided, for example, at the four corners of the cavity 20, and on the other hand on the front and rear surfaces of the plate 2 by means of the side plates 60 and gaskets 61.

[34] Of course, these collector circuits 31, 32 may be formed in different ways depending on the shape of the magnetocaloric material. In the example shown, the plates 30 and their ribs 33, 34 can be obtained by machining, rolling, stamping, electroerosion or similar methods. In another embodiment, the plates 30 may be flat or have a sandwich or spacer interposed between the plates to form a fluid channel. The fluid channel 35 may also be formed by perforations, grooves of different shapes, slits, voids, and combinations of these shapes, which are formed by machining, chemical or ionic or mechanical engraving, shaping, inter-particle spaces. These fluid channels 35 may have dimensions comprised between 0.01mm and 5mm, and preferably equal to 0.15mm, which small dimensions contribute to the creation of a laminar flow of the heat transfer fluid.

[35] With reference to fig. 5A and 5B, at least one heat carrier fluid circuit 51, 52 comprises means for forcing the flow of the heat carrier fluid, such as a pump 53, a thermosiphon or any other equivalent means. This flow can also be made free and natural simply by the temperature difference of the heat transfer fluid.

[36] The chemical composition of the heat transfer fluid is adapted to the desired temperature range and is chosen to obtain maximum heat exchange. For example, pure water is used for positive temperatures and water with an antifreeze agent, such as a glycol agent, added, is used for negative temperatures. The heat generator 1 can thus be freed from the use of any corrosive or harmful fluid to humans and/or their environment.

[37] Each heat carrier fluid circuit 51, 52 comprises discharge means for discharging the thermal and cold energy respectively collected for heating or cooling, such as a thermal heat exchanger 55 and a cold heat exchanger 56, or any other equivalent means. Likewise, each circuit 51, 52 comprises a switching member, such as a two-way electric valve 57, 58 or similar, in order to place the respective thermal element 3 in the respective circuit 51, 52. Of course, the control of these electrically operated valves 57, 58 is synchronized with the rotation of the magnet 40, as will be explained below. Said conversion means can also be integrated in the plate 2 by machining and/or moulding and assembly of the component parts, the conversion being achieved by magnetic attraction to a piston, a ball or the like movable between the two parts forming the valve.

[38] The operation of the heat generator 1 according to the invention is described with reference to fig. 5A and 5B, which fig. 5A and 5B schematically show two operating cycles of the heat generator 1 and, for the sake of simplicity, carry four thermal elements 3 and two pairs of magnets 40. In this example, the recovery means comprise only a single pump 53 provided on the hot circuit 51, and the two circuits, hot circuit 51 and cold circuit 52, are connected as a closed loop: the hot circuit 51 of the heat transfer fluid connects the outlet Sf of the cold heat exchanger 56 with the inlet Ec of the hot heat exchanger 55, while the cold circuit 52 connects the outlet Sc of the hot heat exchanger 55 with the inlet Ef of the cold heat exchanger 56. Two completely independent circuits 51, 52 may also be provided, each forming a closed loop. In this case, each circuit 51, 52 includes its own pump 53. In each case, the flow direction of the heat transfer fluid in the two circuits 51, 52 is preferably opposite. For the sake of simplicity, the hot and cold circuits are indicated with 51, 52, part of which are internal to the heat generator 1 and indicated with 21 and 22, integrated in the panel 2.

[39] In the first operating cycle shown in fig. 5A, the magnet 40 faces two thermal elements 3(1), 3(3) which generate heat under the action of the magnetic field, and the other two thermal elements 3(2), 3(4) cool because they are not subjected to the action of the magnetic field. The electric valves 57, 58 oscillate into a first position which allows the thermal elements 3(1), 3(3) generating heat to be connected in series in the thermal circuit 51 and the thermal elements 3(2), 3(4) cooling to be connected in series in the cold circuit 52, the circuit in which the heat transfer fluid moves being represented by the solid lines. The outlet Sf of the cold heat exchanger 56 is connected to the inlet Ec (1) of the heat element 3(1) via the electric valve 58, the outlet Sc (1) of the heat element 3(1) is connected to the inlet Ec (3) of the heat element 3(3), and the outlet Sc (3) of the heat element 3(3) is connected to the inlet Ec of the heat exchanger 55. The thermal circuit 51 moves the heat transfer fluid in the thermal collector circuits 31 of the thermal elements 3(1), 3(3), the others being inactive. Similarly, the outlet Sc of the hot heat exchanger 55 is connected to the inlet Ef (4) of the thermal element 3(4) via the electric valve 57, the outlet Sf (4) of the thermal element 3(4) is connected to the inlet Ef (2) of the thermal element 3(2), and the outlet Sf (2) of the thermal element 3(2) is connected to the inlet Ef of the cold heat exchanger 56. The cold circuit 52 moves the heat transfer fluid in the cold collector circuit 32 of the thermal elements 3(2), (3) (4), the others being inactive. This period is rapid and lasts between a few milliseconds and 20 milliseconds, and preferably 1 second, corresponding to the time that the magnet 40 passes before the thermal elements 3(1) and 3 (3).

[40] When the magnets leave them to reach the front of the thermal elements 3(2) and 3(4), the motorised valves 57, 58 swing to a second position shown in figure 5B, corresponding to a second operating cycle in which the magnets 40 face the other two thermal elements 3(2), 3(4) which heat up under the action of the magnetic field, the first two thermal elements 3(1) and 3(3) cooling down because they are no longer subjected to the action of the magnetic field. The electric valves 57, 58, which oscillate into their second position, place the heat-generating thermal elements 3(2), 3(4) in the hot circuit 51 and the cooled thermal elements 3(1), 3(3) in the cold circuit 52, the circuit in which the heat transfer fluid moves being represented by the solid lines. The outlet Sf of the cold heat exchanger 56 is connected to the inlet Ec (2) of the thermal element 3(2) via the electric valve 58, the outlet Sc (2) of the thermal element 3(2) is connected to the inlet Ec (4) of the thermal element 3(4), and the outlet Sc (4) of the thermal element 3(4) is connected to the inlet Ec of the thermal heat exchanger 55. The hot circuit 51 allows the heat transfer fluid to flow in the hot collector circuits 31 of the thermal elements 3(2), (3), (4), the others being inactive. Similarly, the outlet Sc of the hot heat exchanger 55 is connected to the inlet Ef (3) of the heat element 3(3) via the electric valve 57, the outlet Sf (3) of the heat element 3(3) is connected to the inlet Ef (1) of the heat element 3(1), and the outlet Sf (1) of the heat element 3(1) is connected to the inlet Ef of the cold heat exchanger 56. The cold circuit 52 moves the heat transfer fluid in the cold collector circuit 32 of the thermal elements 3(1), 3(3), the others being inactive. The fast cycle corresponds to the time that magnet 40 passes before thermal elements 3(2) and 3 (4). When the magnet leaves the thermal elements 3(2) and 3(4) to reach the thermal elements 3(1) and 3(3) again, the electric valves 57, 58 swing to the first position shown in fig. 5A, so that the first operating cycle starts again.

[41] The use of a liquid, rather than a gas, as the heat transfer fluid can be dispensed with by the use of a check valve. An example can be seen in fig. 5A and 5B, where the two circuits, hot circuit 51 and cold circuit 52, converge at the inlets Ec and Ef of the hot heat exchanger 55 and cold heat exchanger 56, respectively. The heat transfer fluid, which is a liquid, is incompressible and is therefore naturally introduced into the closed circuit and not into the open circuit.

[42] From this description it is clear that both circuits, namely the hot circuit 51 and the cold circuit 52, are active and dynamic in both operating cycles, as are the thermal elements 3. In addition, the heat-carrying fluid responsible for recovering the heat energy is limited to this function, as is the heat-carrying fluid responsible for recovering the cold energy. Since there is no mixing of the heat transfer fluids of different temperatures, as is the case in the prior art, the two hot and cold circuits 51, 52 are separate, in particular at the collecting circuits 31, 32 in the hot element 3, and therefore without any heat exchange and without thermal mixing between the circuits. The new technique can thus greatly reduce heat loss, can speed up the operating cycle, increase the power of the heat generator 1, and achieve very good thermal efficiency, and requires very little energy since little power is required to rotate the magnet 40.

[43] In addition, this technique of separation of the hot circuits 21, 31, 51 and the cold circuits 22, 32, 52 allows to use cycles called "AMR", i.e. for each new operating cycle of the heat generator 1, the temperature difference between the temperatures at the beginning and at the end of the cycle increases on the hot circuit 51 and on the cold circuit 52, respectively, so as to reach heating and cooling temperature levels higher than those of generators of the type known today. In addition, the heat generator 1 of the present invention does not present any danger to personnel and the environment. In fact, if the heat transfer fluid is missing in the hot circuit 51 and in the cold circuit 52, there is no longer a heat exchange and therefore no risk of any heat leakage (evaporation thermal).

[44]Possibility of industrial application:

[45] the heat generator 1 finds application in any technical field requiring heating, tempering, cooling, air conditioning, such as in household appliances for refrigerators and freezers, and in air conditioning and heating for industrial and domestic use, even in vehicles, in windows and freezer cabinets for freezing in agri-foodstuffs, in air-conditioned cellars and in freezing chambers of any type.

[46] The invention is not limited to the described embodiments but extends to any modifications and variants that are obvious to a person skilled in the art, while remaining within the scope of protection defined in the appended claims. In particular, the illustrated shapes and number of the thermal elements 3 and the magnets 40, the way of forming the collector circuits 31, 32 and of integrating the hot circuit 21 and the cold circuit 22 in the plate 2 may vary.

Claims (20)

1. Thermal generator (1) of magnetocaloric material, comprising: at least one fixed support (2) carrying at least two thermal elements (3) of magnetocaloric material; a magnetic member (4) movable with respect to the thermal element (3) to subject the thermal element to a magnetic field variation to change its temperature; and a thermal and cold energy recovery means (5) recovering the thermal and cold energy emitted by the thermal elements (3) and comprising at least two distinct circuits (51, 52), a "hot" circuit (51) and a "cold" circuit (52), in each of which a heat-carrying fluid flows, each circuit (51, 52) being connected to at least one heat exchanger (55, 56) capable of discharging the recovered thermal or cold energy and to conversion means (57, 58), the conversion means (57, 58) being arranged for placing the respective thermal elements (3) alternately in the circuits (51, 52),

characterized in that each thermal element (3) comprises a fluid channel (35), said fluid channels (35) forming at least two distinct collector circuits (31, 32), a "hot" collector circuit (31) and a "cold" collector circuit (32), wherein the heat carrier fluid of a hot circuit (51) responsible for collecting the thermal energy emitted by a thermal element (3) subjected to a magnetic field flows in said "hot" collector circuit (31), while the heat carrier fluid of a cold circuit (52) responsible for collecting the cold energy emitted by a thermal element (3) not subjected to a magnetic field flows in said "cold" collector circuit (32), said heat carrier fluid moving alternately in one or the other collector circuit (31, 32) depending on whether said thermal element (3) is subjected to a magnetic field and whether it emits thermal or cold energy.

2. Generator according to claim 1, characterised in that said thermal element (3) is at least partially made of magnetocaloric material at least in a shape chosen in the group: a solid block, a stack of solid blocks or plates (30), a combination of particles, a porous block, a stack of porous blocks or plates, a combination of these shapes.

3. A generator according to claim 2, characterised in that said collector circuits (31, 32) are each formed by a plurality of fluid channels (35) distributed in the thickness of said thermal element (3) to provide a large heat exchange area.

4. Generator according to claim 3, characterised in that said fluid channel (35) has a small size comprised between 0.01mm and 5mm, and preferably equal to 0.15mm, and is suitable for generating a flow of said heat carrying fluid through said thermal element (3), which flow is substantially laminar.

5. A generator according to claim 3, characterised in that the orientation of the fluid channels (35) of the two collector circuits (31, 32) of each thermal element (3) is different.

6. A generator according to claim 3, characterised in that the fluid channels (35) of the two collector circuits (31, 32) of each thermal element (3) are oriented substantially parallel.

7. A generator according to claim 3, characterised in that said fluid channel (35) is formed at least by a formation selected from the group comprising: perforations, grooves, slits, voids, combinations of these shapes, formed by machining, chemical or ionic or mechanical engraving, shaping, interlayers between blocks or plates, spaces between particles.

8. Generator according to claim 1, characterised in that said fixed support comprises at least a plate (2) provided with: at least two openings forming a cavity (20) to receive the thermal element (3) therein; and at least two series of ducts (21, 22) forming part of said hot (51) and cold (52) circuits of heat carrier fluid and opening into each cavity (20) through an inlet and an outlet for each heat carrier fluid circuit (51, 52), said inlets and outlets being suitable for communicating with respective fluid channels (35) of the thermal element (3), that is to say two inlets and two outlets for each cavity (20).

9. Generator according to claim 8, characterised in that said ducts (21, 22) are formed by grooves distributed on at least one of the surfaces of said plate (20); and the heat generator (1) comprises at least one side plate (60) attached to the surface of the plate (2) to block and seal the ducts (21, 22).

10. A generator according to claim 4, characterized in that said thermal element (3) and said cavity (20) have complementary engagement shapes.

11. The generator of claim 10, wherein the complementary engagement shapes are substantially parallelepipedal; each side of said cavity (20) comprising an inlet or an outlet of one of said hot (51) and cold (52) circuits of heat transfer fluid; and each side of the thermal element (3) comprises an inlet or an outlet of one of its collector circuits (31, 32).

12. Generator according to claim 11, characterised in that a gap of 0.05 to 15mm, and preferably equal to 1mm, is provided in each side between the cavity (20) and the thermal element (3), forming a heat carrier fluid distribution chamber extending over the thickness of the thermal element (3); and a sealing mechanism is located in each corner of the cavity (20).

13. A generator according to claim 1, characterized in that it comprises an even number of thermal elements (3) distributed substantially circularly around the central axis (B) of said support (2); the magnetic member (4) is connected to a drive member that rotates around the center axis (B).

14. Generator according to claim 13, characterised in that said magnetic means (4) comprise a number of magnets (40) corresponding to the number of thermal elements (3), these magnets (40) being associated in pairs and being located on each side of said thermal elements (3) so as to subject one (3) of the two to the magnetic field.

15. A generator according to claim 14, characterised in that said thermal elements (3) are arranged in mutual proximity so that pairs of magnets (40) run from one row of thermal elements (3) to the other without cutting off the magnetic field.

16. Generator according to claim 1, characterised in that the heat transfer fluid of the hot circuit (51) and of the cold circuit (52) flow in opposite directions.

17. Generator according to claim 1, characterised in that said means for recovering heat and cold energy comprise means (53) for forcing the flow of said heat-carrying fluid provided on at least one of said heat-carrying fluid circuits (51, 52).

18. Generator according to claim 17, characterised in that said hot circuit (51) and cold circuit (52) are connected in a closed loop, said hot circuit (51) of the heat-carrying fluid connecting the outlet (Sf) of the cold heat exchanger (56) with the inlet (Ec) of the hot heat exchanger (55), and said cold circuit (52) of the heat-carrying fluid connecting the outlet (Sc) of the hot heat exchanger (55) with the inlet (Ef) of the cold heat exchanger (56).

19. Generator according to claim 1, characterised in that said means for recovering heat and cold energy comprise means (53) for forcing the flow of the heat-carrying fluid on each circuit (51, 52) of heat-carrying fluid, which are independent and each of which forms a closed loop.

20. Generator according to claim 1, characterised in that said conversion means comprise at least one valve (57, 58) provided on each of the hot (51) and cold (52) circuits of the heat carrier fluid and arranged for connecting in series one or the other of the collector circuits (31, 32) of the hot element (3) depending on whether the hot element (3) is subjected to a magnetic field and releases heat or cold.