Patent Description:
Heat regenerators are a special form of heat exchanger that serve for intermittent thermal storage and heat transfer between the working (heat-transfer) fluid and the regenerator material (matrix). In general, we distinguish between two types of heat regenerators: static heat regenerators (<FIG>) and moving heat regenerators. Static regenerators have a porous structure through which the working fluid oscillates. The fluid transfers heat to the porous structure or absorbs the stored heat from the porous structure. The first application of a static regenerator can be traced back to Robert Stirling in <NUM>. Therefore, it is a well-known technology.

In technologies such as Stirling or thermo-acoustic devices the working fluid (the gas) oscillates (up to >=<NUM>) through the porous matrix of the regenerator. In this case on one side of the regenerator there is heat sink (or a hot heat exchanger) through which the heat is transferred out of the system. On the other side of the regenerator, there is a heat source (or cold heat exchanger) through which the heat is transferred to the system. Here it makes sense to mention the technology of pulsed tubes. These, for instance, can be seen in the following patents (<CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>), <CIT>)). <CIT>, which is considered as the closest prior art, discloses a thermoacoustic energy conversion system comprising an encasing and at least one assembly of two heat exchangers with a regenerator sandwiched there between arranged in the encasing.

Several different heat regenerator designs can be found in the technical literature (<NPL>; <NPL>; <NPL>; <NPL>; <NPL>).

All the currently known solutions and designs of heat regenerators need to establish a temperature difference (usually a large difference) between the heat source and the heat sink. If this condition is not fulfilled the device will not operate. This requires a particular design and construction for the porous matrix of the heat regenerator that enables a sufficiently large heat transfer surface to act between the regenerator matrix and the working fluid as well as the appropriate length of the heat regenerator.

The flow of the working fluid in all known examples takes the form of oscillation along the length of a heat regenerator (<FIG>). The larger the number of thermodynamic cycles per unit of time (frequency) during which the heat is transferred or absorbed to/from the regenerator, the higher should be the velocity of the working fluid. An increase in the frequency increases the power density of the device, i.e., the specific power per unit mass of regenerator material. Since the regenerator matrix represents a porous structure, it is well known to the expert that the rapid oscillation of the working fluid through the porous structure leads to higher pressure losses, which are a consequence of the viscous forces (this is especially problematic for a working fluid in liquid form). As a consequence, the pressure losses also represent the internal generation of heat as well as a significantly decreased energy efficiency with respect to the device.

Heat regenerators are also used in caloric technologies, which can be further divided to magnetocaloric, electrocaloric, elastocaloric, barocaloric and multicaloric. And for all these mentioned caloric technologies, a special sort of regenerator is used, which has the property that under the influence of an external change of applied force (i.e., pressure, stress) or field (i.e., electric, magnetic), their temperature can be caused to decrease or increase. We refer to these regenerators as active caloric regenerators. The first people to introduce the idea of an active (magnetocaloric) regenerator were <CIT>).

Also in caloric regenerators the working fluid oscillates through the porous matrix in the direction of the temperature gradient, which means along the regenerator. Long-term research in this specific field led to the conclusion that for the efficient transfer of heat (in the case of a liquid as the working fluid) the porous structure should have a porosity of between <NUM> and <NUM> % (<NPL>).

For the efficient transfer of heat in caloric regenerators, liquids are usually applied as the heat transfer fluids (i.e., water, water with freezing suppressants, oils, metals in the liquid state, secondary refrigerants, refrigerants, etc.). For the highest possible power density, the working fluid in the active caloric regenerator should oscillate as fast as possible through the mentioned regenerator. The regenerator has to have a very high heat transfer surface, which consequently means a low porosity of the regenerator. Since liquids have a higher viscosity and density than gases, the oscillation of liquids through active caloric regenerators with a small porosity present difficulties related to the viscous losses. This leads to the undesirable generation of heat (because of the energy dissipation), a very large pressure drop and a related increase in the pumping power needed for the fluid's oscillation. Both the pumping power and the energy dissipation limit the energy efficiency of active caloric regenerators. In order to maintain the relatively high energy efficiency of the caloric regenerator, the frequency of operation should be limited to below <NUM> (i.e., the number of thermodynamic cycles per unit of time).

This is why most of the caloric regenerators operate at low frequencies. This can also be seen from <FIG>. The usual type of magnetocaloric regenerator does not enable energy-efficient operation at high frequencies (number of thermodynamic cycles per unit of time). Following the curve for the specific power per unit of mass for the magnetocaloric material, this will start to decrease at higher frequencies of operation, in the theoretical example of <FIG>, this is between <NUM> and <NUM>. The reason for this is the already-mentioned fluid friction and the generation of heat due to energy dissipation. If the porosity of the regenerator is increased, the viscous losses will be smaller; however, the heat transfer surface will be also smaller. A more obvious influence of the losses, compared to the cooling power, can be observed in a decrease of the coefficient of performance (COP) of the cooling cycle (the ratio of the cooling power to the total input power for the cooling system). Without considering the pumping power, the COP can be substantially higher. The reason for such a substantial decrease of energy efficiency is therefore the pumping losses, which are the result of the viscous losses due to the oscillation of the working fluid along the porous structure of the active regenerator. The higher the frequency, the larger these losses.

An overview of the technical literature, including patents and patent applications (i.e. <NPL>; <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>) points to the fact that all caloric regenerators are designed and constructed in such a way that the fluid oscillates along the regenerator; therefore, in the direction in which in the whole regenerator (that can also consist of different materials) is in steady-state operation a temperature gradient is established.

Despite the fact that the oscillation of the working fluid along the regenerator's matrix leads to heat generation and large viscous losses, there is no patent, no patent application and no technical literature published anywhere in the world that suggests another method for the motion of the fluid through the regenerator can be applied.

The method of heat transfer with a unidirectional fluid flow in an embedded structure of the heat regenerator based on this invention brings about a new principle for the operation of passive and active regenerators, and enables substantially lower viscous (pressure) losses for fluid pumping, compared to any existing method. The primary characteristic of this invention is in the fact that the working fluid does not oscillate along the regenerator matrix (the direction of the temperature gradient that is established in the total regenerator assembly), but oscillates perpendicularly to the longitudinal axis of the regenerator (perpendicular to the direction of the temperature gradient in the total regenerator assembly).

In the method of this invention two (primary and secondary) fluids are applied. These two fluids serve for the heat transfer in the embedded structure of the regenerator, which consists of multiple hydraulically separated segments of regenerator matrices and four heat exchangers: 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 primary (first) fluid P oscillates along the width of the porous structure of the regenerator and transfers heat from the primary cold heat exchanger PH into the primary hot heat exchanger PT. In such an operation an equal volume of fluid acts in one thermodynamic cycle on a much shorter path than is the case with any currently known solution (which is schematically shown in <FIG>). The secondary fluid circulates (unidirectional flow) and flows through all four heat exchangers: PH, PT, SH, ST.

The embedded structure of the heat regenerator, which operates on the basis of the presented method, is composed of:.

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

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.

For a simpler explanation of the operating principle of the presented heat-transfer method using this invention, <FIG> 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.

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:.

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

<FIG> and <FIG> 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> is established using electro-mechanical elements.

The primary hot heat exchanger PT and the primary cold heat exchanger PH are positioned in housing <NUM> between the elements <NUM> 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 <NUM> (shown in <FIG>) with hydraulically separated segments.

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.

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

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.

The porous regenerative material of the regenerator <NUM> 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.

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.

The porous regenerative material of the regenerator <NUM> 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.

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.

The porous regenerative material of the regenerator <NUM> 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.

The number of hydraulically separated segments is lower than <NUM>,<NUM>, preferably between <NUM> and <NUM>,<NUM>, more preferably between <NUM> and <NUM> and even more preferably between <NUM> and <NUM>.

<FIG> show different design examples of the electromechanical elements for the oscillation of the fluid flow of the primary (first) fluid P.

<FIG> shows the first design concept of the mechanism for the oscillation of the fluid flow of the primary (first) fluid P from <FIG>. This concept involves the piezo-electric element <NUM> and the hydraulic displacement amplifier <NUM>. The hydraulic displacement amplifier <NUM> 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 <NUM> and the piston <NUM> 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 <NUM> and hydraulic displacement amplifier <NUM>, where on one side there is a piston <NUM> and a membrane, and with a piston <NUM>' and a membrane and a spring <NUM> on the other side.

<FIG> shows the second design concept of the mechanism of the fluid-flow oscillation of the primary (first) fluid P from <FIG>. The concept is based on the similar solution that is shown in <FIG>; 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>. However, in this design, the amplification is performed by the mechanical displacement amplifier. The mechanical displacement amplifiers, which are based on the leverage <NUM>, are mostly applied in practice. When the composite piezoelectric element <NUM> 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 <NUM> provides the basis for the motion of the primary (first) fluid P.

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

<FIG> shows the fourth design mechanism of the oscillation of the fluid flow of the primary (first) fluid P from <FIG>. Both heat exchangers, PT and PH, are positioned like in the design concept described in <FIG>. However, the design concept of the high-frequency pulsation comprises the brushless DC electromotor <NUM> and the rotor <NUM>, to which the mechanical connection is eccentrically attached. This transforms the rotational movement of the electromotor <NUM> 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 <NUM> 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.

<FIG> shows the fifth design concept of the oscillation of the fluid flow of the primary (first) fluid P from <FIG>. Both heat exchangers, PT and PH, are positioned like in the case described in <FIG>. However, in this case the oscillation of the fluid flow of the primary (first) fluid P is enabled by electromagnet <NUM> 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 <NUM>' with the membrane and spring <NUM> are positioned. When the electric current flows through the electromagnet <NUM>, this attracts the piston <NUM> with the membrane. During the motion of piston <NUM> and the membrane towards the electromagnet <NUM> the spring <NUM> is simultaneously compressed. After the disconnection of the electromagnet <NUM>, the spring <NUM> enables the return of the piston <NUM> and the membrane in the starting position. The force of the spring <NUM> 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 <NUM> there is a fast return of the piston <NUM> with membrane to the starting position.

<FIG> shows the sixth design concept of the oscillation of the fluid flow of the primary (first) fluid P from <FIG>. This concept requires one pump <NUM> with a constant displacement of the fluid and a <NUM>/<NUM> directional valve <NUM>. The pump with the constant fluid displacement <NUM> in the primary circuit pushes the fluid through the valve <NUM>, 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 <NUM> 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.

<FIG> shows the seventh design concept of the oscillation of the fluid flow of the primary (first) fluid P from <FIG>. This concept consists of two pumps, <NUM> and <NUM>, 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 <NUM> and <NUM> 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>.

<FIG> shows the eighth design concept of the oscillation of the fluid flow of the primary (first) fluid P from <FIG>. This concept comprises four on/off <NUM>/<NUM> directional valves, <NUM>, <NUM>, <NUM>, and <NUM>, pump <NUM> and safety valve <NUM>. The valves <NUM>, <NUM>, <NUM>, and <NUM> are electronically controlled in such a way that the direction of the flow through the regenerator is periodically changed. In <FIG> all the <NUM>/<NUM> directional valves <NUM>, <NUM>, <NUM>, and <NUM> 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 <NUM>/<NUM> directional valves <NUM>, <NUM>, <NUM>, and <NUM> 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 <NUM> pushes the primary (first) fluid P through the opened valve <NUM> in the regenerator. From the regenerator, the primary (first) fluid P returns to the suction part of the pump through the opened valve <NUM>. The valves <NUM> and <NUM> 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 <NUM>/<NUM> directional valves <NUM>, <NUM>, <NUM>, and <NUM>. In this case the valve <NUM> is opened and the primary (first) fluid P of the primary circuit flows from the pump <NUM> to the other side of the regenerator (in <FIG> 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 <NUM> through the opened valve <NUM>. The fluid flow of the secondary (second) fluid S can be the same as in <FIG>.

<FIG> shows the ninth design concept of the oscillation of the fluid flow of the primary (first) fluid P from <FIG>, 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 <NUM>/<NUM> directional valve <NUM>. The pump <NUM> operates with unidirectional flow and continuously, whereas with the pulsating opening and closing <NUM>/<NUM> directional valve <NUM>, 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> shows the state, where the <NUM>/<NUM> directional valve <NUM> is opened. The pump <NUM> 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 <NUM> is higher than it is before the entrance to the valve <NUM>, which is evident from the diagram p-x.

<FIG> shows the pressure conditions when the <NUM>/<NUM> directional valve <NUM> is closed for a short period while the pump <NUM> 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 <NUM>/<NUM> directional valve <NUM>. The pressure in the vicinity and before the valve <NUM> is at this moment higher than the pressure on the pressure side of the pump <NUM>, which is shown in the diagram p-x. Because of the higher pressure on the side of the valve <NUM>, the flow of the fluid changes its direction and flows through the regenerator in the opposite direction towards the pump <NUM>. With a periodic opening and closing of the valve <NUM>, the oscillatory fluid flow of the primary (first) fluid P can be established through the regenerator.

<FIG> and <FIG> 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>, 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>.

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>.

<FIG> shows the tenth design concept for the oscillation of the fluid flow of the primary (first) fluid P in <FIG>, which is based on the principle of electrowetting. In the case of <FIG>, 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.

<FIG> shows an example of the regenerator, which consists of an ordered structure of plates <NUM> (e.g., parallel plates, zig-zag plates, and plates with specially treated surfaces). In this case on the surfaces <NUM>, <NUM>' of ordered structures, the electrodes <NUM> are positioned. In the <FIG> an example of the regenerator is shown; it consist of the porous matrix <NUM> (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 <FIG> 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 <NUM> are positioned on the surface of the channels in both heat exchangers PT and PH.

The operation of the principle of electrowetting from <FIG> and <FIG> 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).

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 <NUM> and the fluid of the droplets, which are separated into two parts: one part of the droplets <NUM> is positioned in the hot heat exchanger PT, another part of the droplets <NUM> is positioned in the cold heat exchanger PH. The regenerator <NUM>, 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 <NUM> is still present. The primary (first) fluid P in the form of droplets <NUM>, which is positioned in the hot heat exchanger PT, undergoes movement into the structure of the regenerator <NUM>, due to the change of the electric potential on electrodes <NUM>. Because of the heat transfer, the primary (first) fluid P in the form of droplet <NUM>, absorbs heat from the caloric material of the regenerator <NUM>. Then, under the unchanged force or field, the primary (first) fluid P in the form of droplets <NUM>, 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 <NUM>, which is positioned in the cold heat exchanger PH, undergoes movement into the structure of the regenerator <NUM>, due to the change of the electrical potential on the electrodes <NUM>. Because of the heat transfer, the primary (first) fluid P in the form of droplet <NUM>, transfers heat to the caloric material in the regenerator <NUM>. 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 <NUM>.

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 <NUM> is not separated into two parts. The droplets <NUM> are joined together in one part and are positioned in the hot heat exchanger PT and the regenerator <NUM> or in the cold heat exchanger PH and regenerator. In the first process the caloric material of the regenerator <NUM> 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 <NUM>, which is at that moment positioned in regenerator <NUM>, absorbs heat due to the heat transfer from the caloric material. Some of the droplets <NUM> are at that moment in the cold heat exchanger PH. In the second process, the regenerator <NUM> is still under an unchanged external field or force. The primary (first) fluid P in the form of droplets <NUM>, undergoes movement towards the hot heat exchanger PT, due to the change of the electrical potential on the electrodes <NUM>. The droplets <NUM>, which absorbed heat in the regenerator <NUM>, transfer the heat in the hot heat exchanger PT to the secondary (second) fluid S. The droplets <NUM>, which were positioned in the cold heat exchanger PH, enter the regenerator <NUM>. In the third process, the regenerator <NUM> is exposed to the negative change of the external field or force. Therefore, at the end of the process <NUM>, 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 <NUM>, positioned in the regenerator <NUM>, 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 <NUM>, performs movement towards the cold heat exchanger PH, due to the change of the electrical potential on the electrode <NUM>. The droplets <NUM>, which were in the regenerator <NUM>, perform movement towards the cold heat exchanger PH, where they absorb heat from the secondary (second) fluid S. The droplets <NUM>, which were positioned in the hot heat exchanger PH, enter the regenerator <NUM>.

<FIG> 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.

<FIG> show an example of the segment of the regenerator, when this consists of the parallel plates <NUM> on which the electrodes <NUM> are positioned.

<FIG>shows an example of the parallel plates <NUM>, where the droplets <NUM> are separated between the plates <NUM>. <FIG> shows an example of the parallel plates <NUM> where the droplets <NUM> are not separated with the plates <NUM>, but are positioned next to each other with respect to the plane of the plates <NUM>.

<FIG> 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 <NUM> are positioned. The extended surface serves for better heat transfer between the droplets <NUM> and the plates <NUM> of the regenerator <NUM>.

<FIG> shows the case of the parallel plates <NUM> where the droplets are separated between the plates <NUM>.

<FIG> shows the case of the parallel plates <NUM>, where the droplets <NUM> are not separated with the parallel plates <NUM>, and are positioned next to each other with respect to the plane of the plates <NUM>.

<FIG> shows a detail of the plates <NUM> from <FIG>, where the surface for the transfer of heat is shown more explicitly.

<FIG> and <FIG> show the first example of the segment of the regenerator <NUM>, consisting of a caloric material with round channels for the primary (first) fluid P (in the form of droplets).

<FIG> shows the bottom side of the regenerator <NUM> 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>) of the regenerator <NUM>.

<FIG> shows the cross-section of the regenerator <NUM> 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 <NUM> and the primary (first) fluid P.

<FIG> shows another example of the segment of the regenerator <NUM>, consisting of a caloric material with the round channel of the primary (first) fluid P (in the form of droplets).

<FIG> shows the bottom side of the regenerator <NUM>, 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 <NUM>. The round channels being next to each other, is mainly to provide an increase in the surface for heat transfer between the regenerator <NUM> and the primary (first) fluid P.

<FIG> show different possibilities for the segments of the caloric regenerator, consisting of caloric material, where the surface has different forms of channels.

<FIG> shows the meandering channels in the regenerator <NUM>, <FIG> the zig-zag channels, <FIG> the labyrinth channels and <FIG> the cross channels. In <FIG> and <FIG>, the electrodes <NUM> are shown on the bottom side of the regenerator <NUM> 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 <NUM>. In comparison with straight channels, this kind of approach leads to a substantially larger heat-transfer surface between the regenerator <NUM> and the primary (first) fluid P.

<FIG> and <FIG> 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).

<FIG> shows the state when the porous structure of the regenerator is exposed to the positive change of the external field or force.

<FIG> 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> 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 <NUM> (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.

The process shown in <FIG> is the inverse of the above-described process. The regenerator <NUM> 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 <NUM> (where it cools due to heat transfer), and then into the heat exchanger PT, where it absorbs heat from the secondary (second) fluid S.

<FIG> shows the case of the structure of the heat exchanger PT and the heat exchanger PH, between which the regenerator <NUM> is positioned.

<FIG> 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.

<FIG> 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.

<FIG> 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.

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.

<FIG> 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.

<FIG> 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.

<FIG> 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.

Claim 1:
A method of heat transfer in an embedded structure of a heat regenerator, that is based on:
a plurality of segments formed from a porous regenerative material, where the segments are hydraulically separated, and where a temperature gradient through a particularly hydraulically separated segment is smaller than the temperature gradient established along the embedded structure of the heat regenerator;
a structure for flow of the primary (first) fluid (P) that flows forward and backward through each of the hydraulically separated segments, consisting of porous regenerative material, with the flow forward and backward in a direction that is approximately perpendicular to a direction of the temperature gradient, which is established along the embedded structure of the heat regenerator;
a structure for flow of secondary (second) fluid (S) that flows uni-directionally in a hydraulic circuit, which connects heat source and heat sink with primary hot and cold heat exchanger (PT and PH),
a primary hot heat exchanger (PT), which is hydraulically connected with a first side of hydraulically separated segments, the hydraulically separated segments formed from the porous regenerative material;
a primary cold heat exchanger (PH), which is hydraulically connected with a second side of hydraulically separated segments, the hydraulically separated segments formed from the porous regenerative material;
a second hot heat exchanger (ST) that represents the connection with a heat sink;
a second cold heat exchanger (SH) that represents the connection with a heat source;
the primary (first) fluid (P) that flows forward and backward in parallel through each of the hydraulically separated segments consisting of porous regenerative material and whereas the primary (first) fluid (P) releases or absorbs the heat from porous regenerative material;
the primary (first) fluid (P) that transfers heat from the in-parallel hydraulically separated segments of porous regenerative material to the primary hot heat exchanger (PT);
the primary (first) fluid (P) that transfers heat from the primary cold heat exchanger (PH) to the in-parallel hydraulically separated segments of porous regenerative material;
a secondary (second) fluid (S) that flows uni-directionally in a hydraulic circuit, which connects heat source and heat sink with primary hot and cold heat exchanger (PT and PH).