METHOD FOR HEAT TRANSFER IN THE EMBEDDED STRUCTURE OF A HEAT REGENERATOR AND THE DESIGN THEREOF

Abstract

The subject of this invention is a method of heat transfer in the embedded structure of a heat regenerator and the design thereof. It regards the related heat regenerators, which operate on the principle of the described method and enable a reduction of the pressure drop due to the fluid flow through the heat regenerator and consequently an increase of the power density. The concept of the operation of the heat regenerator by this invention, in which for the oscillation of the flow of the primary (first) fluid (P), electromechanical elements are applied. In the housing (1) between the elements (2) for the oscillation of the primary (first) fluid (P), there are positioned a primary hot heat exchanger (PT) and a primary cold heat exchanger (PH). In the direction of the arrow (A) the unidirectional flow of the secondary (second) fluid (S) flows from the heat sink into the primary cold heat exchanger (PH). In the direction of the arrow (B) the unidirectional flow of the secondary (second) fluid (S) exits from the primary cold heat exchanger (PH) and flows towards the heat source. Meanwhile, in the direction of the arrow (C), the unidirectional flow of the secondary (second) fluid S enters the primary hot heat exchanger (PT) and exits in the direction of the arrow (D) as the unidirectional flow of the secondary (second) fluid S of the primary hot heat exchanger (PT) towards the heat sink. Between both primary heat exchangers, (PT) and (PH), the porous regenerative material is positioned, which is part of the regenerator 4, with the hydraulically separated segments.

Claims

1. A method of heat transfer in the embedded structure of a heat regenerator that is based on A larger number of segments consisting of porous regenerative material, where the segments are hydraulically separated, and where the temperature gradient through the particularly hydraulically separated segment is smaller than the temperature gradient established along the embedded structure of the heat regenerator (4); A flow of the primary (first) fluid (P) that oscillates through each of the hydraulically separated segments, consisting of porous regenerative material, with the oscillation in the direction that is approximately perpendicular to the direction of the temperature gradient, which is established along the embedded structure of the heat regenerator (4), whereas the primary (first) fluid (P) transfers or absorbs heat flux from the first and the second heat exchanger, A first heat exchanger, which is hydraulically connected with the first side of hydraulically separated segments, consisting of porous regenerative material; A second heat exchanger, which is hydraulically connected with the second side of the hydraulically separated segments, consisting of porous regenerative material; A heat exchanger that represents the connection with the heat source; A heat exchanger that represents the connection with the heat sink; A secondary (second) fluid (S) that flows through the heat exchanger and represents the connection with the heat source, flows through the first heat exchanger, flows through the heat exchanger, which represents the connection with the heat sink, and flows through the second heat exchanger; Mechanisms, devices or physical phenomena that enable the flow of the primary (first) fluid (P) and secondary (second) fluid (S).

2. A heat regenerator that operates on the basis of the method based on the claim 1, characterized in that that comprise: A porous structure of the regenerator, consisting of hydraulically separate segments, which disable the longitudinal flow of the primary fluid, which is the working fluid in the regenerator; A primary hot heat exchanger (PT), which enables heat transfer from the oscillatory flow of the primary (first) fluid (P) to the unidirectional flow of the secondary (second) fluid (S) on the hot side of the porous structure of regenerator; A primary cold heat exchanger (PH), which enables heat transfer from the unidirectional flow of the secondary (second) fluid (S) to the oscillatory flow of the primary (first) fluid (P) on the cold side of the porous structure of the regenerator; A secondary cold heat exchanger (SH), which is positioned on the side of the heat source and serves for the transfer of heat into the secondary (second) fluid (S); A secondary hot heat exchanger (ST), which is positioned on the side of the heat sink and serves for the heat absorption from the secondary (second) fluid (S); A secondary (second) fluid (S), which connects the heat source and the heat sink through the heat exchangers (PT) and (PH); A flow of the secondary (second) fluid (S) through the primary hot heat exchanger (PT), which is counter-directed to the flow of the secondary (second) fluid (S) in the primary cold heat exchanger (PH); A system for pumping the secondary (second) fluid (S); A system for the oscillation of the primary (first) fluid (P).

3. A heat regenerator that operates on the basis of the method from claim 1 and from claim 2, characterized in that the porous regenerative material of the regenerator (4) in hydraulically separated segments is a caloric (magnetocaloric, barocaloric, elastocaloric, electrocaloric, multicaloric) material.

4. A heat regenerator that operates on the basis of the method from claim 1 and from claim 2, characterized in that the porous regenerative material of the regenerator (4) in hydraulically separated segments is a caloric (magnetocaloric, barocaloric, elastocaloric, electrocaloric, multicaloric) material, combined with at least one other material chosen from the group of metals, ceramics, glasses, composites of carbon or of carbon materials, polymers or composites of polymer materials, metamaterials, and liquid crystals.

5. A heat regenerator that operates on the basis of the method from claim 1 and claim 2, characterized in that the porous regenerative material in the regenerator (4) in the hydraulically separated segment is not caloric, and it is chosen from the group of desiccant materials such as: activated alumina, aerogel, benzophenone, bentonite, calcium chloride, calcium oxide, calcium sulphate, cobalt chloride, copper sulphate, lithium chloride, lithium bromide, magnesium sulphate, magnesium perchlorate, molecular sieve, potassium carbonate, potassium hydroxide, silica gel, sodium, sodium chlorate, sodium chloride, sodium hydroxide, sodium sulphate, and sucrose.

6. A heat regenerator that operates on the basis of the method by claim 1 and claim 2, characterized in that the porous regenerative material in the regenerator (4) in the hydraulically separated segment is not caloric and it is chosen from the group of materials, such as: metals, ceramics, glasses, composites of carbon or of carbon materials, polymers or composites of polymer materials, cement, concrete, rock, or metamaterials or a combination of at least two of the materials mentioned here.

7. A heat regenerator that operates on the basis of the method by claim 1 and claim 2 and claims 3, 4, and 5, characterized in that the porous regenerative material in the regenerator (4) in the hydraulically separated segments represents the combination of at least two materials from claims 3, 4, and 5.

8. A heat regenerator that operates on the basis of the method by claim 1 and claim 2, characterized in that the number of hydraulically separated segments is lower than 10,000, preferably between 1000 and 10,000, more preferably between 100 and 1000 and even more preferably between 10 and 100.

9. A heat regenerator that operates on the basis of the method by claim 1 and claim 2, characterized in that that the primary (first) fluid (P) is chosen from the group of liquids, liquid metals, gases or refrigerants.

10. A heat regenerator that operates on the basis of the method by claim 1 and claim 2, characterized in that that the secondary (second) fluid (S) is chosen from the group of liquids, liquid metals, gases or refrigerants.

11. A heat regenerator that operates on the basis of the method by claim 1 and claim 2, characterized in that that the mechanism, device, or physical phenomena, which enables the flow of the primary, is based on mechanical actuation, capillary effect, electro-kinetics, electro-hydrodynamics, magneto-hydrodynamics, electrowetting or magneto wetting or the principle of the heat pipe.

12. A heat regenerator that operates on the basis of the method by claim 1 and claim 2, characterized in that the mechanism, device, or a physical phenomenon, which enables the flow of the secondary fluid, is based on the mechanical actuation, capillary effect, electro-kinetics, electro-hydrodynamics, magneto-hydrodynamics, electrowetting or magneto wetting, the principle of the heat pipe or a vapour-compression process.

13. A heat regenerator that operates on the basis of the method by claim 1 and claim 2, characterized in that the primary hot heat exchanger (PT), primary cold heat exchanger (PH), secondary hot heat exchanger (ST) and the secondary cold heat exchanger (SH) consist of materials chosen from the group of metals, polymers, carbon or carbon materials, such are carbon, graphite, graphene, composite materials, ceramic materials, cement, concrete or rocks or rock materials or their combination.

14. A heat regenerator that operates on the basis of the method by claim 1 and claims 3, and 4, characterized in that the device, which comprises caloric material in hydraulically separated segments, is chosen from the group of caloric refrigerators, caloric heat pumps or caloric power generators.

15. A heat regenerator that operates on the basis of the method by claim 1 and claim 5, characterized in that the device, which comprises desiccant materials in hydraulically separated segments, is chosen from the group of adsorption refrigerators, adsorption heat pumps or adsorption drying device, absorption refrigerator, absorption heat pump or absorption drying device.

16. A heat regenerator that operates on the basis of the method by claim 1 and by claims 2, 3 and 4 and 5 and 6, characterized in that the device, which applies material in hydraulically separated segments, is chosen from the group of: mechanical Stirling refrigerator, mechanical Stirling heat pump, mechanical Stirling power generator, thermoacoustic refrigerator, thermoacoustic heat pump, thermoacoustic power generator, pulsed tube refrigerator, Gifford-McMahon (GM) cycle, furnace or boiler, catalytic converter or chemical reactor.

17. A heat regenerator that operates on the basis of the method by claim 1 and claims 2 and 7, characterized in that the device, which applies material in hydraulically separated segment, is chosen from the group of devices that are listed in claims 15, 16 and 17.

Description

[0024] The invention is described in more detail on the basis of design examples and the corresponding figures, which show:

[0025] FIG. 1 example of a static heat regenerator with oscillation of the fluid flow (state of the art);

[0026] FIG. 2 graph of a caloric device's operation in terms of the frequency (number of thermodynamic cycles per unit of time);

[0027] FIG. 3 heat regenerator operating principle as the method of heat transfer by this invention;

[0028] FIG. 4A fundamental operation example of the invention, where the oscillatory flow of the primary (first) fluid P is based on the operation of electro-mechanical elements;

[0029] FIG. 4B implemented operating example of the invention, where the oscillatory flow of the primary (first) fluid P is based on the operation of electro-mechanical elements;

[0030] FIG. 5 implemented example of pumping of the primary (first) fluid P by means of the piezo-electric element and the hydraulic displacement amplifier;

[0031] FIG. 6 implemented example of the pumping of the primary (first) fluid P by means of the piezo-electric element and the mechanical displacement amplifier;

[0032] FIG. 7 implemented example of the pumping of the primary (first) fluid P by means of the piezo-electric actuator without the displacement amplifier;

[0033] FIG. 8 implemented example of pumping of the primary (first) fluid P by means of the electromotor;

[0034] FIG. 9 implemented example of pumping of the primary (first) fluid P by means of the electromagnet;

[0035] FIG. 10 schematic of the system with the one pump and the 4/2 directional valve in the primary circuit;

[0036] FIG. 11 schematic of the concept with two pumps;

[0037] FIG. 12 schematic of the concept with four 2/2 on/off directional valves;

[0038] FIG. 13A schematic of the oscillating fluid flow along the heat regenerator with the pressure wave generation by means of the continuous pump operation and opening/closing of the 2/2 directional valve; example of open 2/2 directional valve; fluid flow pulse in the direction of the pump operation;

[0039] FIG. 13B schematics of the oscillating fluid flow along the heat regenerator with the pressure wave generation by means of the continuous pump operation and opening/closing of the 2/2 directional valve; example of closed 2/2 directional valve; fluid flow pulse in the counter-direction of the pump operation;

[0040] FIG. 14A fundamental concept of the invention where the oscillation of the primary (first) fluid P is based on the principle of the electro-hydrodynamics or electro-kinetics of the fluid;

[0041] FIG. 14B implemented operating example of the invention where the oscillation of the primary (first) fluid P is based on the principle of the electro-hydrodynamics or electro-kinetics of the fluid;

[0042] FIG. 15A depiction of the hydraulically separated segments of the whole assembly of the heat regenerator, which is in contact with heat exchangers PT and PH, built from the ordered structures (e.g., parallel plates, zig-zag plates, honeycomb, plates with treated surface);

[0043] FIG. 15B depiction of the hydraulically separated segment of the whole assembly of the heat regenerator, which is in contact with heat exchangers PT and PH, built from a porous matrix (e.g., packed bed, foam, bundles of wires);

[0044] FIG. 16A example of the segment of the caloric regenerator, built from parallel plates of magnetocaloric material with electrodes positioned on top and where the droplets are separated between the plates;

[0045] FIG. 16B example of the segment of the caloric regenerator, built from parallel plates of magnetocaloric material with electrodes on top and where the droplets are next to each other on the plate's surface;

[0046] FIG. 17A example of a segment of the caloric regenerator, built from parallel plates of magnetocaloric material with an extended surface with electrodes positioned on the top and where the droplets are separated between the plates;

[0047] FIG. 17B example of the segment of the caloric regenerator, built from parallel plates of magnetocaloric material with an extended surface with electrodes positioned on top and where the droplets are next to each other on the plate's surface;

[0048] FIG. 17C example of the segment of the caloric regenerator, built from parallel plates of magnetocaloric material with an extended surface with electrodes, where the close-up picture of the plates with an extended surface is shown;

[0049] FIG. 18A shows the bottom side of the caloric regenerator where the electrodes are applied, by which the primary (first) fluid P is moved by means of a change in the electric potential (based on the electrowetting principle) through pyramid-like channels;

[0050] FIG. 18B cross-section of the caloric regenerator, where the pyramid-like channels are positioned next to each other;

[0051] FIG. 19A shows the bottom side of the caloric regenerator where the electrodes are applied, by which the primary (first) fluid P is moved by means of a change in the electric potential (based on the electrowetting principle) through round channels;

[0052] FIG. 19B cross-section of the caloric regenerator, where the round channels are positioned next to each other;

[0053] FIG. 20A bottom and top sides of the caloric regenerator, the surface of which is covered with channels of different shapes;

[0054] FIG. 20B bottom side of the caloric regenerator, the surface of which is covered with meandering channels;

[0055] FIG. 20C top side of the caloric regenerator, the surface of which is covered with labyrinth channels;

[0056] FIG. 20D bottom side of the caloric regenerator, the surface of which is covered with zig-zag channels;

[0057] FIG. 20E top side of the caloric regenerator, the surface of which is covered with labyrinth channels;

[0058] FIG. 20F bottom side of the caloric regenerator, the surface of which is covered with labyrinth channels;

[0059] FIG. 20G top side of the caloric regenerator, the surface of which is covered with labyrinth channels;

[0060] FIG. 20H bottom side of the caloric regenerator, the surface of which is covered with cross channels;

[0061] FIG. 21 schematic of the fluid oscillation mechanism based on the electro-osmosis principle; primary (first) fluid P flows in the heat exchanger PH; regenerator is subjected to the positive field or force change; detail A shows electro-hydrodynamic conditions of the primary (first) fluid P inside the heat exchanger;

[0062] FIG. 22 schematic of the fluid-oscillation mechanism based on the electro-osmosis principle; primary (first) fluid P flows in the heat exchanger PH; regenerator is subjected to the negative field or force change; detail A shows electro-hydrodynamic conditions of the primary (first) fluid P inside the heat exchanger;

[0063] FIG. 23 example of the heat exchanger PT and the heat exchanger PH structures; the heat regenerator is positioned between PT and PH;

[0064] FIG. 24 example of the heat exchanger PT or the heat exchanger PH structure;

[0065] FIG. 25A example of the whole structure of the heat exchanger PT or the heat exchanger PH;

[0066] FIG. 25B example of the whole structure of the heat exchanger PT or the heat exchanger PH in cross-section;

[0067] FIG. 26 example of the heat exchanger PT or the heat exchanger PH structure;

[0068] FIG. 27 example of the heat exchanger PT or the heat exchanger PH structure with perpendicular channels for the electro-hydrodynamic pumping of the primary (first) fluid P;

[0069] FIG. 28 example of the heat exchanger PT or the heat exchanger PH structure with zig-zag channels for the electro-hydrodynamic pumping of the primary (first) fluid P;

[0070] FIG. 29 example of the heat exchanger PT or the heat exchanger PH structure with triangular channels for the electro-hydrodynamic pumping of the primary (first) fluid P.

[0071] The method of heat transfer in the embedded structure of the heat regenerator presented by this invention and different design examples are described in the following text in more detail.

[0072] For a simpler explanation of the operating principle of the presented heat-transfer method using this invention, FIG. 3 shows the operation of the embedded structure of the heat regenerator. The method of heat regeneration for the oscillation of the fluid flow of the primary (first) fluid P is performed perpendicularly to the direction of the temperature gradient in the total embedded structure of the regenerator and with the unidirectional fluid flow of the secondary (second) fluid S, which connects the heat source and the heat sink via the secondary hot heat exchanger ST and the secondary cold heat exchanger SH.

[0073] The method of this invention can be explained by the example of the operation of the caloric cooling device. The operation of this device can be described by four basic thermodynamic processes: [0074] magnetization, polarization, compressive or tensile load deformation of the caloric regenerator. The temperature of the matrix of the caloric regenerator is increased; [0075] heat transfer under a constant external field or constant external force applied to the caloric regenerator. The primary (first) fluid P in this phase of its oscillation flows through the caloric regenerator in the direction towards the primary hot heat exchanger PT. The primary (first) fluid P absorbs the heat from the hydraulically separated segments of the caloric regenerator and transfers the heat to the primary hot heat exchanger PT. The primary heat exchanger PT transfers the heat to the secondary (second) fluid S; [0076] demagnetization, depolarization, compressive or tensile stress release of the caloric regenerator. The temperature of the matrix of the caloric regenerator is decreased; [0077] heat transfer in the absence of a field or force applied to the caloric regenerator. The primary (first) fluid P in this phase of its oscillation flows through the caloric regenerator in the direction towards the primary cold heat exchanger PH. The primary (first) fluid P transfers heat to the hydraulically separated segments of the caloric regenerator and absorbs heat in the primary cold heat exchanger PH. The primary cold heat exchanger PH absorbs the heat from the secondary (second) fluid S.

[0078] The thermodynamic processes can also be different, depending on the type of thermodynamic cycle.

[0079] FIGS. 4A and 4B show the concept of the operation of the heat regenerator using this invention, for which the oscillation of the flow of the primary (first) fluid P from FIG. 3 is established using electro-mechanical elements.

[0080] The primary hot heat exchanger PT and the primary cold heat exchanger PH are positioned in housing 1 between the elements 2 for the oscillation of the fluid flow of the primary (first) fluid P. The unidirectional fluid flow of the secondary (second) fluid S is in the direction of the arrow A, from the heat sink ST to the cold heat exchanger PH. The unidirectional fluid flow of the secondary (second) fluid S is in the direction of the arrow B from the primary cold heat exchanger PH towards the heat source SH. The unidirectional fluid flow of the secondary (second) fluid S is in the direction of the arrow C from the heat source SH to the primary hot heat exchanger PT. The unidirectional fluid flow of the secondary (second) fluid S is in the direction of the arrow D from the primary hot heat exchanger PT towards the heat sink ST. Between both primary heat exchangers, PT and PH, there is positioned a porous regenerative material (matrix), which is a part of the regenerator 4 (shown in FIG. 3) with hydraulically separated segments.

[0081] The primary hot heat exchanger PT, the primary cold heat exchanger PH, the secondary hot heat exchanger ST and the secondary cold heat exchanger SH consist of materials chosen from the groups of metals, polymers, carbons and carbon materials (carbon, graphite, graphene), such as composite materials, ceramic materials, cement, concrete or rock material and their combinations.

[0082] The primary (first) fluid P and the secondary (second) fluid S are chosen from the groups of liquids, liquid metals, gases or refrigerants.

[0083] The mechanism, the device or the physical phenomenon that enables the fluid flow of the primary (first) fluid P can be based on a mechanical motion, a capillary effect, electro-kinetics, electro-hydrodynamics, magneto-hydrodynamics, electrowetting or magnetowetting or the heat-pipe principle. The mechanism, device or physical phenomenon that enables the fluid flow of the secondary (second) fluid S is based on a mechanical motion, a capillary effect, electro-kinetics, electro-hydrodynamics, magneto-hydrodynamics, electrowetting or magnetowetting, a heat-pipe principle or a vapour-compression process.

[0084] The porous regenerative material of the regenerator 4 in the hydraulically separated segments can be a caloric (magnetocaloric, electrocaloric, elastocaloric, barocaloric, multicaloric) material, combined with any other material chosen from the group of metals, ceramics, glass, composites, carbon or carbon materials, polymers or composites of polymer materials, metamaterials, liquid crystals.

[0085] When the device is made up of caloric or a combination of caloric and other materials in the form of the porous regenerative matrix in the hydraulically separated segments or parts, then the device that can be created on this basis belongs to the group of caloric refrigerators or coolers, caloric heat pumps or caloric power generators.

[0086] The porous regenerative material of the regenerator 4 in the hydraulically separated segments can also be chosen from the group of desiccant materials such as activated alumina, aerogel, benzophenone, bentonite, calcium chloride, calcium oxide, calcium sulphate, cobalt chloride, copper sulphate, lithium chloride, lithium bromide, magnesium sulphate, magnesium perchlorate, molecular sieve, potassium carbonate, potassium hydroxide, silica gel, sodium, sodium chlorate, sodium chloride, sodium hydroxide, sodium sulphate, and sucrose.

[0087] When the device is made up of desiccant material, such as the porous regenerative material matrix in hydraulically separated segments, then the device that can be created on this basis belongs to the group of adsorption refrigerators or chillers, adsorption heat pumps or adsorption drying devices, absorption refrigerators or chillers, absorption heat pumps or absorption dryers, or catalytic converters, or chemical reactors.

[0088] The porous regenerative material of the regenerator 4 of the hydraulically separated segments can be chosen from the group of materials that are not caloric and include the following: metals, ceramics, glass, composites, carbon and carbon materials, polymers or composites from polymer materials, or metamaterials, or minerals, or cement, concrete, rocks, or a combination of at least two of the materials mentioned here. When the device comprises such materials in the form of a porous regenerator in the hydraulically separated segments, then the device that can be created on this basis belongs to the group of mechanical Stirling refrigerators or coolers, mechanical Stirling heat pumps, mechanical Stirling power generators, thermoacoustic refrigerators or coolers, thermoacoustic heat pumps, thermoacoustic power generators, pulsed tube refrigerators, Gifford-McMahon (GM) refrigerators, furnaces or boilers, catalytic converters or chemical reactors.

[0089] The number of hydraulically separated segments is lower than 10,000, preferably between 1000 and 10,000, more preferably between 100 and 1000 and even more preferably between 10 and 100.

[0090] FIGS. 5-12 show different design examples of the electromechanical elements for the oscillation of the fluid flow of the primary (first) fluid P.

[0091] FIG. 5 shows the first design concept of the mechanism for the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3. This concept involves the piezo-electric element 5 and the hydraulic displacement amplifier 6. The hydraulic displacement amplifier 6 operates under the principle of the different contact surfaces. It is fulfilled with incompressible liquid, which transforms the small displacement of the large surfaces into the large displacement of smaller surfaces. The concept with the funnel allows small displacements of the piezoelectric element 5 and the piston 7 with the membrane are additionally strengthened. This makes it possible to reach the desired fluid flow through the structure of the regenerator. Both heat exchangers, PT and PH, are placed in the housing between the piezoelectric element 5 and hydraulic displacement amplifier 6, where on one side there is a piston 7 and a membrane, and with a piston 7′ and a membrane and a spring 8 on the other side.

[0092] FIG. 6 shows the second design concept of the mechanism of the fluid-flow oscillation of the primary (first) fluid P from FIG. 3. The concept is based on the similar solution that is shown in FIG. 5; however, with the difference being that the displacement-amplifying mechanism is different. Both the heat exchangers, PT and PH, are positioned similarly to the concept presented in FIG. 5. However, in this design, the amplification is performed by the mechanical displacement amplifier. The mechanical displacement amplifiers, which are based on the leverage 9, are mostly applied in practice. When the composite piezoelectric element 10 is charged by electric current, it will be elongated. When the electrical current is disconnected, the piezo-electric element contracts. In this way the oscillatory motion of the piezo-electric element 10 provides the basis for the motion of the primary (first) fluid P.

[0093] FIG. 7 shows the third design concept of the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3. Both heat exchangers, PT and PH, are positioned like in the case described in FIG. 5. However, in the case presented in FIG. 7, the concept is based on the piezo-electric element 11, which is directly connected to the piston 12 with the membrane without the displacement amplifier. In order to achieve the desired displacements of the membrane, a larger number of piezoelectric elements 11 arranged in series is required.

[0094] FIG. 8 shows the fourth design mechanism of the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3. Both heat exchangers, PT and PH, are positioned like in the design concept described in FIG. 5. However, the design concept of the high-frequency pulsation comprises the brushless DC electromotor 13 and the rotor 14, to which the mechanical connection is eccentrically attached. This transforms the rotational movement of the electromotor 13 into the linear motion of the membrane. The membrane consequently oscillates the fluid through the structure of the regenerator. The reason for the selection of the DC brushless electromotor 13 is that these motors provide silent operation, are more reliable, have a higher energy efficiency and a larger ratio between the moment and the mass compared to a brushed electromotor. One of the important features is also that they do not require an air flow for the cooling and can therefore be closed into the housing, which prevents any contact with dirt and water.

[0095] FIG. 9 shows the fifth design concept of the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3. Both heat exchangers, PT and PH, are positioned like in the case described in FIG. 5. However, in this case the oscillation of the fluid flow of the primary (first) fluid P is enabled by electromagnet 15 positioned on one side, which can be switched on and off in a manner that the oscillation with the desired frequency is established, while on the other side, the piston 7′ with the membrane and spring 8 are positioned. When the electric current flows through the electromagnet 15, this attracts the piston 7 with the membrane. During the motion of piston 7 and the membrane towards the electromagnet 15 the spring 17 is simultaneously compressed. After the disconnection of the electromagnet 15, the spring 17 enables the return of the piston 7 and the membrane in the starting position. The force of the spring 17 has to be substantially smaller than the force of the electromagnet, so as to not disturb its operation. However, the force should be sufficiently large so that during the disconnection of the electromagnet 15 there is a fast return of the piston 7 with membrane to the starting position.

[0096] FIG. 10 shows the sixth design concept of the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3. This concept requires one pump 18 with a constant displacement of the fluid and a 4/2 directional valve 19. The pump with the constant fluid displacement 18 in the primary circuit pushes the fluid through the valve 19, which periodically changes the flow direction in the primary circuit through the structure of the regenerator. Therefore, in the cycle when the heat is generated, the fluid is pushed in one direction, and when the structure of the regenerator is cooled, the fluid is pushed in another direction. The second pump 20 in the secondary circuit constantly pushes the fluid through separated layers of the regenerator in one direction through the cold heat exchanger PH and the hot heat exchanger PT.

[0097] FIG. 11 shows the seventh design concept of the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3. This concept consists of two pumps, 21 and 22, which are positioned one on each side of the regenerator structure and provide counter-fluid-flow with regards to each other. The operation of this mechanism is based on electronic control, which, with the appropriate frequency, periodically turns the pumps 21 and 22 on and off. In this way the change of the direction of the fluid flow in the structure of the regenerator can be achieved. The secondary fluid flow can be the same as in the case illustrated by FIG. 10.

[0098] FIG. 12 shows the eighth design concept of the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3. This concept comprises four on/off 2/2 directional valves, 23, 24, 25, and 26, pump 27 and safety valve 28. The valves 23, 24, 25, and 26 are electronically controlled in such a way that the direction of the flow through the regenerator is periodically changed. In FIG. 12 all the 2/2 directional valves 23, 24, 25, and 26 are shown in their zero-position, which means there is no need for an electric current on the electromagnet for this position. The zero position of all four 2/2 directional valves 23, 24, 25, and 26 is chosen in such a way that they provide the first direction of the flow of the primary (first) fluid P through the regenerator. The pump 27 pushes the primary (first) fluid P through the opened valve 23 in the regenerator. From the regenerator, the primary (first) fluid P returns to the suction part of the pump through the opened valve 26. The valves 24 and 25 are closed for the first direction of the flow of the primary (first) fluid P. In order to change the direction of the flow of the primary (first) fluid P, the control electronics switches on all four electromagnets of the 2/2 directional valves 23, 24, 25, and 26. In this case the valve 25 is opened and the primary (first) fluid P of the primary circuit flows from the pump 27 to the other side of the regenerator (in FIG. 12 from the upper side). The exit of the primary (first) fluid P from the regenerator is in this second case from the bottom side. The primary (first) fluid P is returning to the suction part of the pump 27 through the opened valve 24. The fluid flow of the secondary (second) fluid S can be the same as in FIG. 10.

[0099] FIG. 13 shows the ninth design concept of the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3, which does not require additional electro-mechanical components. The oscillation of the fluid flow of the primary (first) fluid P is based on pressure waves, which are the consequence of sudden openings and closings of the gap in the 2/2 directional valve 28. The pump 29 operates with unidirectional flow and continuously, whereas with the pulsating opening and closing 2/2 directional valve 28, pressure waves are created, which travel through the system. Therefore, in the system, the direction of the fluid flow of the primary (first) fluid P can be oscillating. FIG. 13A shows the state, where the 2/2 directional valve 28 is opened. The pump 29 pushes fluid in the x-direction towards the heat sink and also through the porous structure of the regenerator. Therefore, the pressure on the pressure side of pump 29 is higher than it is before the entrance to the valve 28, which is evident from the diagram p-x.

[0100] FIG. 13B shows the pressure conditions when the 2/2 directional valve 28 is closed for a short period while the pump 29 still operates. Because of the sudden closing of the fluid flow of the primary (first) fluid P, a sudden increase in the pressure occurs in the vicinity and before the 2/2 directional valve 28. The pressure in the vicinity and before the valve 28 is at this moment higher than the pressure on the pressure side of the pump 29, which is shown in the diagram p-x. Because of the higher pressure on the side of the valve 28, the flow of the fluid changes its direction and flows through the regenerator in the opposite direction towards the pump 29. With a periodic opening and closing of the valve 28, the oscillatory fluid flow of the primary (first) fluid P can be established through the regenerator.

[0101] FIGS. 14A and 14B show the case of the operation of the concept of this invention, for which the oscillation of the fluid flow of the primary (first) fluid P from FIG. 3, for which the concept of the electro-hydrodynamics or electro-kinetics of the fluid is applied. In the middle of the device the regenerator with the hydraulically separated segments of the fluid flow of the primary (first) fluid P is positioned. To the left and right of the regenerator two heat exchangers, PT and PH, are positioned. They serve for the heat transfer between the primary (first) fluid P and secondary (second) fluid S. Both heat exchangers, PH and PT, and the regenerator provide the channels for the primary (first) fluid P, and have electrodes for the electro-hydrodynamic propulsion of the primary (first) fluid P. The primary (first) fluid P is in this case in the form of a plural number of droplets, which perform the oscillatory motion between the regenerator and the heat exchangers. The motion is achieved with a change of the electric potential on the different electrodes. The system for the oscillation of the primary (first) fluid P is not shown in FIG. 14.

[0102] The secondary (second) fluid S circulates (unidirectional flow) and flows through all four heat exchangers; therefore, flowing through the primary cold heat exchanger PH, the primary hot heat exchanger PT, the secondary cold heat exchanger SH and the secondary hot heat exchanger ST. The system for the pumping of the secondary (second) fluid S is shown in FIG. 14B.

[0103] FIG. 15 shows the tenth design concept for the oscillation of the fluid flow of the primary (first) fluid P in FIG. 3, which is based on the principle of electrowetting. In the case of FIG. 15, the detail shows one of the hydraulically separated parts of the whole assembly of the heat regenerator, which is in contact with the heat exchanger PT and the heat exchanger PH.

[0104] FIG. 15A shows an example of the regenerator, which consists of an ordered structure of plates 32 (e.g., parallel plates, zig-zag plates, and plates with specially treated surfaces). In this case on the surfaces 30, 30′ of ordered structures, the electrodes 31 are positioned. In the FIG. 15B an example of the regenerator is shown; it consist of the porous matrix 34 (e.g., packed bed, foam, bundles of wires). In this case electrodes with a certain distance in between are inserted into the heat regenerator. In both cases in FIGS. 15A and 15B the heat exchanger PT and the heat exchanger PH are designed in such a way that it enables the construction of channels for the oscillation of the fluid flow of the primary (first) fluid P. The electrodes 31 are positioned on the surface of the channels in both heat exchangers PT and PH.

[0105] The operation of the principle of electrowetting from FIGS. 14A and 14B is performed in two different ways. In both cases, because of an easier explanation, it is assumed that the material of the regenerator matrix is caloric (magnetocaloric or electrocaloric or elastocaloric or barocaloric or multicaloric).

[0106] The first principle operates in four processes of the operation of one thermodynamic cycle. In the first process, the primary (first) fluid P is in the form of droplets 35 and the fluid of the droplets, which are separated into two parts: one part of the droplets 35 is positioned in the hot heat exchanger PT, another part of the droplets 35 is positioned in the cold heat exchanger PH. The regenerator 4, which consists of caloric material, is exposed to the positive change of the external force or field (the temperature of the caloric material increases). In the second process, the external field or force on the regenerator 4 is still present. The primary (first) fluid P in the form of droplets 35, which is positioned in the hot heat exchanger PT, undergoes movement into the structure of the regenerator 4, due to the change of the electric potential on electrodes 31. Because of the heat transfer, the primary (first) fluid P in the form of droplet 35, absorbs heat from the caloric material of the regenerator 4. Then, under the unchanged force or field, the primary (first) fluid P in the form of droplets 35, undergoes movement back to the heat exchanger PT, where it transfers heat to the secondary (second) fluid S. The third process represents the change of the external field or force that acts on the caloric material, to the state without a field or without a force on the caloric material (the temperature of the caloric material decreases). In the fourth process of the operation, the primary (first) fluid P in the form of droplets 35, which is positioned in the cold heat exchanger PH, undergoes movement into the structure of the regenerator 4, due to the change of the electrical potential on the electrodes 31. Because of the heat transfer, the primary (first) fluid P in the form of droplet 35, transfers heat to the caloric material in the regenerator 4. Then, with the unchanged field or force, the primary (first) fluid P undergoes movement back to the cold heat exchanger PH, where it absorbs heat from the secondary (second) fluid S. The movement also occurs due to the change of the electrode potential on the electrodes 31.

[0107] The second case also operates in the four processes of a thermodynamic cycle, with the difference that the primary (first) fluid P in the form of droplets 35 is not separated into two parts. The droplets 35 are joined together in one part and are positioned in the hot heat exchanger PT and the regenerator 4 or in the cold heat exchanger PH and regenerator. In the first process the caloric material of the regenerator 4 is exposed to the positive change of the field or force (the temperature of the caloric material increases). The primary (first) fluid P in the form of droplets 35, which is at that moment positioned in regenerator 4, absorbs heat due to the heat transfer from the caloric material. Some of the droplets 35 are at that moment in the cold heat exchanger PH. In the second process, the regenerator 4 is still under an unchanged external field or force. The primary (first) fluid P in the form of droplets 35, undergoes movement towards the hot heat exchanger PT, due to the change of the electrical potential on the electrodes 31. The droplets 35, which absorbed heat in the regenerator 4, transfer the heat in the hot heat exchanger PT to the secondary (second) fluid S. The droplets 35, which were positioned in the cold heat exchanger PH, enter the regenerator 4. In the third process, the regenerator 4 is exposed to the negative change of the external field or force. Therefore, at the end of the process 4, the external field or force is no longer present (the temperature of the caloric material decreases). The primary (first) fluid P in the form of droplets 35, positioned in the regenerator 4, transfers heat to the caloric material. The fourth process runs under the unchanged field or force (no field or no force). The primary (first) fluid P in the form of droplets 35, performs movement towards the cold heat exchanger PH, due to the change of the electrical potential on the electrode 31. The droplets 35, which were in the regenerator 4, perform movement towards the cold heat exchanger PH, where they absorb heat from the secondary (second) fluid S. The droplets 35, which were positioned in the hot heat exchanger PH, enter the regenerator 4.

[0108] FIGS. 16 to 22 show the different concepts of the combination of electrodes and caloric material for the different designs for the motion of the primary (first) fluid P that are based on electrowetting.

[0109] FIGS. 16A and 16B show an example of the segment of the regenerator, when this consists of the parallel plates 30 on which the electrodes 31 are positioned.

[0110] FIG. 16 A shows an example of the parallel plates 30, where the droplets 35 are separated between the plates 30. FIG. 16B shows an example of the parallel plates 30 where the droplets 35 are not separated with the plates 30, but are positioned next to each other with respect to the plane of the plates 30.

[0111] FIGS. 17A to 17C show an example of the segment of the regenerator when it consists of parallel plates of the caloric material with an extended surface, on which the electrodes 31 are positioned. The extended surface serves for better heat transfer between the droplets 35 and the plates 30 of the regenerator 4.

[0112] FIG. 17 A shows the case of the parallel plates 30 where the droplets are separated between the plates 30.

[0113] FIG. 17 B shows the case of the parallel plates 30, where the droplets 35 are not separated with the parallel plates 30, and are positioned next to each other with respect to the plane of the plates 30.

[0114] FIG. 17 C shows a detail of the plates 30 from FIG. 17A, where the surface for the transfer of heat is shown more explicitly.

[0115] FIGS. 18A and 18B show the first example of the segment of the regenerator 4, consisting of a caloric material with round channels for the primary (first) fluid P (in the form of droplets).

[0116] FIG. 18A shows the bottom side of the regenerator 4 on which the electrodes are attached. With the change of the electrical potential the primary (first) fluid P (the principle of electrowetting) is moved through the round channels (FIG. 18B) of the regenerator 4.

[0117] FIG. 18B shows the cross-section of the regenerator 4 where the round channels can be seen positioned next to each other. The advantage of such special channels is mainly the increase in the surface for the heat transfer of the regenerator 4 and the primary (first) fluid P.

[0118] FIG. 19 A shows another example of the segment of the regenerator 4, consisting of a caloric material with the round channel of the primary (first) fluid P (in the form of droplets).

[0119] FIG. 19 B shows the bottom side of the regenerator 4, to which the electrodes are attached. With a change of the electrical potential, the primary (first) fluid P (the principle of electrowetting) moves through the round channels of the regenerator 4. The round channels being next to each other, is mainly to provide an increase in the surface for heat transfer between the regenerator 4 and the primary (first) fluid P.

[0120] FIGS. 20A to 20H show different possibilities for the segments of the caloric regenerator, consisting of caloric material, where the surface has different forms of channels.

[0121] FIG. 20B shows the meandering channels in the regenerator 4, FIG. 20D the zig-zag channels, FIG. 20F the labyrinth channels and FIG. 20H the cross channels. In FIGS. 20E and 20G, the electrodes 31 are shown on the bottom side of the regenerator 4 and they serve for the movement of the droplets of the primary (first) fluid P with the principle of electrowetting. Such curved channels are mainly to ensure elongation of the path of the primary (first) fluid P through the regenerator 4. In comparison with straight channels, this kind of approach leads to a substantially larger heat-transfer surface between the regenerator 4 and the primary (first) fluid P.

[0122] FIGS. 21 and 22 show schematics of the mechanism of the oscillation of the fluid flow of the primary (first) fluid P, which is based on electro-osmosis. From both schematics it is evident that the heat exchangers PT and PH are designed in such a way that the channels for the flow of the primary (first) fluid P are exposed to the changing electrical field (change of the polarity).

[0123] FIG. 21 shows the state when the porous structure of the regenerator is exposed to the positive change of the external field or force.

[0124] FIG. 22 shows the state when the porous structure of the regenerator is exposed to the negative change of the field or force. When the regenerator is exposed to the positive change of the field or force, it can be seen in the detail of FIG. 21 that the heat exchanger is in the electrical field, which is positive on the left-hand side (cathode) and negative (anode) on the right. The walls of the channel are charged negatively, and for this reason the positive ions (cations) from the electrolytic primary (first) fluid P flows towards such walls of the channel. At the wall a layer forms, which is saturated with positive cations. Because of the high density of the positive cations, the layer of the primary (first) fluid P moves towards the negative anode on the right-hand side of the channel. Because of the viscous forces this layer also drags other layers of the primary (first) fluid P, which is in the channel. In this way the flow of the primary (first) fluid P is formed and flows from the heat exchanger PT through the regenerator 4 (where primary (first) fluid P absorbs heat) into the heat exchanger PH. In the heat exchanger PH the primary (first) fluid P transfers heat to the secondary (second) fluid S.

[0125] The process shown in FIG. 22 is the inverse of the above-described process. The regenerator 4 is exposed to the negative change of the field or force (the temperature of the caloric material decreases). In the heat exchangers PT and PH, the polarity is changed, and the electrolytic primary (first) fluid P flows from the heat exchanger PH through the regenerator 4 (where it cools due to heat transfer), and then into the heat exchanger PT, where it absorbs heat from the secondary (second) fluid S.

[0126] FIG. 23 shows the case of the structure of the heat exchanger PT and the heat exchanger PH, between which the regenerator 4 is positioned.

[0127] FIG. 24 shows the first example of the structure of the heat exchanger PT or the heat exchanger PH, where the ordered structures for the heat transfer in the channel are applied.

[0128] FIGS. 25A and 25B show the second example of the structure of the heat exchanger PT or the heat exchanger PH, where for the fluid flow of the primary (first) fluid P tubes of round or other cross-sections are applied.

[0129] FIG. 26 shows the third example of the structure of the heat exchanger PT or heat exchanger PH, where for the heat transfer in the zig-zag channel or other ordered structures are applied.

[0130] In all the cases the surface of the channels for the fluid flow in the heat exchanger PT, and/or the surface of the channels for the fluid flow in the heat exchanger PH, can be extended.

[0131] FIG. 27 shows the fourth example of the structure of the heat exchanger PT or heat exchanger PH, where for the movement of the primary (first) fluid P in the form of droplets, the principle of electrowetting is applied. The channels on the side of the primary (first) fluid P consist of electrodes positioned on the walls of these channels. With the change of the electrical potential, the droplets can move to/from the heat exchanger PT or the heat exchanger PH. On the side of the secondary (second) fluid S, the orthogonal channels are shown, through which the secondary (second) fluid S is continuously flowing.

[0132] FIG. 28 shows the fifth case of the structure of the heat exchanger PT or heat exchanger PH, where the motion of the primary (first) fluid P is in the form of droplets, where the electrowetting principle is applied. The channels on the side of primary (first) fluid P consist of electrodes, which are positioned on the walls of these channels. With the change of the electrical potential, the droplets move from/to the heat exchanger PT or the heat exchanger PH. On the side of the secondary (second) fluid S, the zig-zag channels are shown, through which the secondary (second) fluid S is continuously flowing.

[0133] FIG. 29 shows the sixth case of the structure of the heat exchanger PT or heat exchanger PH, where the motion of the primary (first) fluid P is in the form of droplets, where the principle of electrowetting is applied. The channels of the side of the primary (first) fluid P consist of electrodes, which are positioned on their walls. With the change of the electrical potential, the droplets move to/from the heat exchanger PT or heat exchanger PH. On the side of the secondary (second) fluid S triangular channels are shown, through which the secondary (second) fluid S continuously flows.

[0134] The method for heat transfer in the embedded structure of heat regenerator 4 and the designs of the related heat regenerators, which operate on the basis of the method by this invention, applies hydraulically separated segments in the regenerator. This disables the fluid flow along the regenerator 4 (the flow along the regenerator 4 is the state of the art). The fluid flow through the hydraulically separated segments of the regenerator 4 is therefore performed perpendicular to the direction of the temperature gradient, which is, in the steady state, established along the regenerator 4. The application of the fluid flow through the hydraulically separated segments does not fulfil the condition for operating at larger temperature spans. This is due to the fact that particular segments in the direction of the fluid flow can be shorter than the whole length of the regenerator 4. Therefore, for the use of the fluid flow of the primary (first) fluid P through the regenerator 4, each side of the regenerator should be attached to two additional heat exchangers. Whereas the primary (first) fluid P oscillates through the regenerator 4 and transfers/absorbs heat to/from both heat exchangers PT and PH, there is required secondary (second) fluid S, which continuously flows between the heat source and the heat sink. If only the heat exchanger PH or PT is observed, then the direction of the secondary (second) fluid S through one heat exchanger PH is counter-directed to the fluid flow of the secondary (second) fluid S through the heat exchanger PT. In this way, despite the fact that the oscillatory flow of the primary (first) fluid flow P is established perpendicularly to the length of the whole regenerator, a temperature distribution and a temperature span can be achieved, similar to the case with the oscillatory flow of the fluid along the whole length of the regenerator, and therefore without separated hydraulic segments. However, in the proposed method a substantially lower drop of the pressure will be established as this is the case in any of the state of the art solutions.