Dielectric-caloric and / or pyroelectric heat exchanger with improved housing

Abstract

To provide a heat exchanger that is improved with regard to the temperature difference that can be achieved.SOLUTION: A heat exchanger (6) comprises at least one laterally-long substrate (10) that is made of electro-caloric or pyroelectric material and forms at least one channel (14) for a fluid, at least two electrodes (16, 18) at two laterally opposite ends of the at least one substrate (10), and a housing (20) that surrounds the at least one substrate (10) and the at least two electrodes (16, 18) and is provided with at least one fluid connection port (20.1, 20.2). The housing consists of a heat-shrinkable flexible tube (20) and shrinks onto the at least one substrate (10) to form the at least one fluid connection port (20.1, 20.2).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The invention to be described has arisen within the context of a research project entitled "Materials for sensing and energy harvesting", supported by the National Research Fund of Luxembourg (Ref. PRIDE15 / 10935404 / MASSENA).

[0002] The present invention relates to the field of heat exchangers using the dielectric caloric effect. [Background technology]

[0003] The dielectric caloric effect is a phenomenon in which a material exhibits a reversible temperature change in the presence of an applied electric field. It is often considered the physical opposite of the pyroelectric effect. It should not be confused with the magnetocaloric effect or even the thermoelectric effect (particularly the Peltier effect), which require large magnetic fields and powerful, expensive magnets. The thermoelectric effect is the creation of a temperature difference when an electric current is driven through an electrical connection involving two dissimilar conductors. The basic mechanism of the dielectric caloric effect arises from the fact that a voltage raises or lowers the entropy of a system.

[0004] SU840621, a published prior art patent document, discloses a refrigeration or cooling-generating device using the dielectric caloric effect. The device includes a central heat exchanger with a stack of plates made of dielectric caloric material. The plates are spaced apart to form a series of parallel fluid channels between the plates. The dielectric caloric plate stack is surrounded by a housing providing two opposing fluid connection ports. Opposite ends of the dielectric caloric plate stack contact two electrodes connected to a power source. Auxiliary heat exchangers are fluidly connected to each of the two opposing fluid connection ports. A reciprocating positive displacement pump is fluidly connected to each of the two auxiliary heat exchangers to move fluid reciprocally from the central heat exchanger to the first auxiliary heat exchanger and from the central heat exchanger to the second auxiliary heat exchanger as the electrodes are alternately powered on and off.

[0005] The functional principle of the device is as follows: When the power supply to the dielectric calorific plate is turned on, the temperature of the dielectric calorific plate rises, and fluid is transferred from the first auxiliary heat exchanger to the main heat exchanger, thereby heating the fluid. The fluid is then transferred in the opposite direction, i.e., back to the first auxiliary heat exchanger, while the power supply to the dielectric calorific plate is turned off. This means that the temperature of the dielectric calorific plate decreases concomitantly due to heat transfer to the fluid transferred to the first heat exchanger and the release of the electric field. Furthermore, concomitantly, the fluid in the second auxiliary heat exchanger is transferred to the main heat exchanger and receives heat from there. The fluid then returns to the second heat exchanger, as in the first transfer, while the power supply to the dielectric calorific plate is turned on again for the next cycle. The first heat exchanger exhibits an increasing temperature, thereby supplying heat, i.e., heating the medium, while the second heat exchanger exhibits a decreasing temperature, thereby receiving heat, i.e., cooling the medium.

[0006] In the above teachings, the temperature difference that can be achieved in the central heat exchanger is limited to, for example, a few degrees Celsius or a few Kelvin, and is periodic. This means that proper insulation is required. However, the structure of the central heat exchanger in the above teachings exhibits high thermal inertia and poor insulation, thereby reducing the achievable temperature difference. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Soviet Patent Invention No. 840621 (SU840621) Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention is directed to the technical problem of providing a heat exchanger that is improved in terms of the temperature difference that can be achieved. [Means for solving the problem]

[0009] The present invention is directed to a heat exchanger comprising at least one substrate made of a dielectric and / or pyroelectric material and forming at least one channel for a fluid, at least two electrodes on two opposite ends of the at least one substrate, and a housing surrounding the at least one substrate and the at least two electrodes and provided with at least one fluid connection port, the housing being made of a heat-shrinkable flexible tube that shrinks onto the at least one substrate to form the at least one fluid connection port.

[0010] The at least one substrate may consist of at least two, preferably at least three, and more preferably at least four substrates.

[0011] According to a preferred embodiment, the heat shrinkable flexible tubing conforms tightly to at least one substrate.

[0012] According to a preferred embodiment, at least one channel for the fluid presents a main direction along which the heat-shrinkable flexible tube extends.

[0013] According to a preferred embodiment, the two ends of at least one substrate are transverse ends carrying at least two electrodes.

[0014] According to a preferred embodiment, the heat exchanger further comprises an electrical lead connected to the at least two electrodes and extending between at least one outer surface of the at least one substrate and an inner surface of the heat-shrinkable flexible tube.

[0015] According to a preferred embodiment, the electrical leads extend out of the collapsible flexible tube through at least one fluid connection port.

[0016] According to a preferred embodiment, the heat exchanger further comprises at least one hose inside each of the at least one fluid connection port.

[0017] According to a preferred embodiment, the at least one hose is glued to a corresponding fluid connection port.

[0018] The at least one channel may be formed inside the at least one substrate.

[0019] According to a preferred embodiment, the at least one substrate is constructed from a single substrate, and spacers are provided on two opposite sides of the single substrate to form two of the at least one channel for the fluid together with the collapsible flexible tube.

[0020] According to a preferred embodiment, the at least one substrate comprises at least two substrates stacked on top of one another, thereby forming at least one channel for the fluid between the at least two substrates.

[0021] According to a preferred embodiment, each of the at least two electrodes is formed by electrically connecting corresponding ends of at least two substrates together, which may be done by soldering, applying conductive tape, and / or applying conductive paste.

[0022] According to a preferred embodiment, the at least two substrates are spaced apart from each other by spacers arranged at the two ends of the at least two substrates.

[0023] According to a preferred embodiment, these spacers extend along the main direction of at least one channel for the fluid.

[0024] According to a preferred embodiment, additional spacers are provided on two opposite faces of the stack of at least two substrates, thereby forming two of the at least one channel for the fluid together with the collapsible flexible tube.

[0025] The present invention is also directed to a device for heating and / or cooling, comprising: a dielectric mass heat exchanger with a first fluid connection port and a second fluid connection port opposite the first fluid connection port; a first auxiliary heat exchanger fluidly connected to the first fluid connection port; a second auxiliary heat exchanger fluidly connected to the second fluid connection port; a fluid transfer unit configured to transfer fluid back and forth from the dielectric mass heat exchanger to the first auxiliary heat exchanger and from the dielectric mass heat exchanger to the first heat exchanger; and a power source configured to intermittently turn on and off power to the dielectric mass heat exchanger while the fluid transfer unit transfers fluid back and forth, wherein the dielectric mass heat exchanger is in accordance with the present invention.

[0026] According to a preferred embodiment, the device further comprises a first hose extending inside the first fluid connection port and fluidly connected to the first auxiliary heat exchanger; and a second hose extending inside the second fluid connection port and fluidly connected to the second auxiliary heat exchanger.

[0027] The present invention is also directed to a device for generating electrical energy, comprising: a pyroelectric heat exchanger; a heating source; a cooling source; a fluid transfer unit configured to continuously transfer fluid from the heating source to the pyroelectric heat exchanger and from the cooling source to the pyroelectric heat exchanger; and an electrical load configured to collect electrical charge from the pyroelectric heat exchanger while the fluid transfer unit continuously transfers fluid, wherein the pyroelectric heat exchanger is a heat exchanger according to the present invention.

[0028] The electrical load can include a capacitor and a power source configured to apply an electric field to the capacitor prior to each transfer of fluid from the heating source to the pyroelectric heat exchanger.

[0029] According to a preferred embodiment, the fluid transfer unit comprises a reciprocating pump, wherein the reciprocating pump, a heating source, and a cooling source are fluidly connected in series to form a branch circuit, which is fluidly connected to a first fluid connection port of the pyroelectric heat exchanger (6) and to a second fluid connection port of said pyroelectric heat exchanger opposite to the first fluid connection port.

[0030] According to a preferred embodiment, the fluid transfer unit comprises a pump, a first selection valve, and a second selection valve. The heating and cooling sources are arranged in parallel and are fluidly connected to the pyroelectric heat exchanger and the pump via the first and second selection valves to form a closed circuit. The fluid circulating through this circuit selectively passes through the heating or cooling source.

[0031] The present invention is also directed to a method for manufacturing a heat exchanger, comprising the steps of: (a) providing at least one substrate made of a dielectric calorific and / or pyroelectric material to form at least one channel for a fluid; (b) forming at least two electrodes on two opposite ends of the at least one substrate; and (c) providing a housing enclosing the at least one substrate and the at least two electrodes and having at least one fluid connection port. Step (c) comprises inserting the at least one substrate into a heat-shrinkable flexible tube and then heating the heat-shrinkable flexible tube to shrink it onto the at least one substrate to form the at least one fluid connection port. [Effects of the Invention]

[0032] The present invention is particularly interesting in that it substantially reduces the thermal inertia of the heat exchanger, thereby substantially increasing the temperature difference that can be achieved when the heat exchanger is installed in a device for heating and / or cooling, and in a device for generating electrical energy from heating and cooling sources. The internal volume of the heat exchanger does not exhibit dead volume, and the plastic material of the heat-shrinkable flexible tubing forms a first useful insulating barrier, and the size of this plastic material is very limited. The inventors have discovered that the housing of the heat exchanger does not need to support significant pressures or forces, making this solution particularly interesting. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a graph of temperature and voltage illustrating the principle of the dielectric caloric effect. [Figure 2] 1 is a cross-sectional view of a heat exchanger according to the present invention; [Figure 3] 1 is a perspective view of the heat exchanger of the present invention prior to heat shrinking of the shrinkable flexible tubing to form the housing of the heat exchanger. FIG. [Figure 4]1 is a perspective view of a heat exchanger of the present invention integrated into a device for heating and / or cooling; [Figure 5] 1 is a perspective view of a heat exchanger of the present invention integrated into a device for generating electrical energy; [Figure 6] FIG. 1 is a perspective view of a heat exchanger of the present invention integrated into another device for generating electrical energy. DETAILED DESCRIPTION OF THE INVENTION

[0034] The dielectrocaloric effect is an adiabatic and reversible temperature change that occurs in polar materials when an electric field is applied. A large dielectrocaloric effect can be achieved in ferroelectric materials with a perovskite structure because their polarity exhibits a strong dependence on temperature approaching the ferroelectric phase transition temperature (Tc), especially with compositions around the morphotropic boundary (MPB). Furthermore, thin films of the material PZT (a mixture of lead, titanium, oxygen, and zirconium) exhibit a strong dielectrocaloric response; for an electric field change of 480 kV / cm at an ambient temperature of 220 °C, the material cools by as much as about 12 °C.

[0035] Figure 1 graphically illustrates the temperature variation over time in a dielectric caloric material when an electric field is applied. The electric field 2 shows a rectangular outline, i.e., 250 volts, applied for more than 20 seconds. The resulting temperature 4 in the material shows an upper limit that rises by more than 2°C upon application of the electric field, after which the temperature drops back to its initial value due to material relaxation. The temperature then shows a lower limit of approximately the same magnitude as the upper limit when the electric field is removed. The upper and lower temperature behaviors are used herein as the dielectric caloric effect.

[0036] FIG. 2 is a cross-sectional view of a heat exchanger according to the present invention.

[0037] The heat exchanger 6 comprises a stack 8 of substrates 10, e.g., plates, spaced apart by spacers 12 to form fluid channels 14 between the substrates 10. The substrates 10 are made of a dielectric calorific material, such as any one of those described above or any other known to those skilled in the art. The fluid channels 14 are parallel and extend along a main direction of the heat exchanger, perpendicular to the plane of the cross-section. As is apparent, the spacers 12 are positioned adjacent to the lateral edges of the substrates 10. The spacers may represent adhesive layers for bonding onto the substrates 10, thereby enabling the formation of a stable stack 8 of the substrates 10.

[0038] Referring further to FIG. 2 , the lateral ends of the substrates are soldered together on each side, thereby forming electrodes 16 and 18. A voltage can be applied to these electrodes to generate an electric field across each substrate 10. The heat exchanger 6 also includes a housing formed by heat-shrinkable flexible tubing 20, which shrinks over the stack 8 of substrates 10. Heat-shrink tubing, or common heat shrink, is a shrinkable plastic tubing commonly used to insulate wire and provide abrasion resistance and environmental protection for stranded and solid wire conductors, connections, splices, and terminations in electrical work. It is typically made of polyolefin and, when heated, shrinks radially (rather than longitudinally) by 1 / 2 to 1 / 6 of its diameter. In its shrunk state, as illustrated in FIG. 2 , the heat-shrinkable flexible tubing 20 fits tightly over the stack 8 of substrates 10, so that the fluid channels 14 between the substrates 10 are the only possible flow channels along the heat exchanger 6.

[0039] 2, additional spacers 22 may be provided on opposite outer sides of the stack 8 of substrates 10. More specifically, they may be provided on both outer surfaces of the outer substrates in the stack 8 of substrates 10 so as to form fluid channels 14 between the outer surfaces of each of the two substrates and the corresponding inner surfaces of the heat-shrinkable flexible tubing 20. The additional spacers 22 also abut the lateral edges of the corresponding substrates 10.

[0040] As an alternative to the stack of substrates 10 described above, the substrates can be single and both have fluid channels formed therein, i.e., on the inside of the substrate, and / or spacers can be used on opposite sides of the outside of the substrate, such as spacer 22 described above.

[0041] The heat shrinkable flexible tubing 20 is black, but can be a different color.

[0042] 3 is a perspective view of a heat exchanger 6 according to the present invention, with the heat shrinkable flexible tubing 20 not yet shrunk. It can be seen that the heat shrinkable flexible tubing 20 exhibits an inner periphery that is significantly larger than the periphery of the stack 8 of substrates 10. This allows the stack 8 of substrates 10 to be easily inserted into the heat shrinkable flexible tubing 20. The heat shrinkable flexible tubing 20 is then heated and shrunk onto the stack 8 of substrates 10 to form a tight fit, as illustrated in FIG.

[0043] As is evident in FIG. 3, the substrates 10 may extend along a main direction that corresponds to the main direction of the heat exchanger 6 and the main direction of the heat-shrinkable flexible tubes 20, while each substrate 10 may exhibit a series of subsections adjacent to one another along this main direction.

[0044] The manufacturing process of the heat exchanger comprises the following steps: (a) stacking substrates together, preferably with spacers, to form fluid channels between the substrates; (b) forming electrodes on two opposite ends of the substrate and connecting electrical leads thereto; (c) inserting the stack of substrates with electrical leads into a flexible heat shrinkable tube, and then heating the flexible heat shrinkable tube to shrink it onto the stack to form fluid connection ports; may include:

[0045] The above detailed structure is advantageous in that there is no dead volume for the fluid passage, and the walls of the heat-shrinkable flexible tubing provide a good first insulating barrier compared to most current materials used to form housings, such as metal-based materials. The generally cylindrical outer form of the heat exchanger allows for the heat exchanger to be easily surrounded by one or more insulating covers. In this case, the thermal inertia of the heat exchanger is limited to the dielectric calorific base and the heat-shrinkable flexible tubing, while the heat-shrinkable flexible tubing exhibits reduced bulk.

[0046] FIG. 4 illustrates a heat exchanger of the present invention integrated into a device for heating and / or cooling.

[0047] 2 and 3 and described above, a first auxiliary heat exchanger 26 fluidly connected to a first fluid connection port 20.1 of the heat exchanger 6, a second auxiliary heat exchanger 28 fluidly connected to a second fluid connection port 20.2 of the heat exchanger 6, and a fluid transfer unit 30 fluidly interconnecting the first and second auxiliary heat exchangers 26 and 28 and configured to transfer fluid back and forth in two opposite directions. For example, each of the first and second fluid connection ports 20.1 and 20.2 is formed by a heat-shrinkable flexible tube 20. The first auxiliary heat exchanger 26 is fluidly connected to the heat exchanger 6 by a first hose 32. The first hose 32 is inserted into the first fluid connection port 20.1 at a corresponding end of the heat-shrinkable flexible tube 20. The heat shrinkable flexible tube 20, once shrunk onto the hose 32, forms a tight connection. Similarly, the second auxiliary heat exchanger 28 is fluidly connected to the heat exchanger 6 by a second hose 34. The second hose 34 is inserted into the second fluid connection port 20.2 at the other corresponding end of the heat shrinkable flexible tube 20. The heat shrinkable flexible tube 20, once shrunk onto the hose 34, forms a tight connection. An adhesive or any other type of sealant can be applied to increase the mechanical strength and / or liquid-tightness of the connection.

[0048] Two electrical leads or wires 36 and 38 are connected to the electrodes (not visible in FIG. 4 but visible in FIG. 2 as reference numerals 16 and 18) and extend through the first and second fluid connection ports 20.1 and 20.2 along the main direction of the heat exchanger. More specifically, each electrical lead 36 and 38 extends between one of the fluid connection ports 20.1 / 20.2 and the corresponding hose 32 / 34. The electrical leads 36 and 38 are connected to a switchable power supply 40, which allows the power supply to the dielectric calorific substrate to be selectively turned on and off.

[0049] The operation of the device in FIG. 4 is as follows: In a first cycle, the power supply 40 is switched on to supply power to the dielectric calorific substrate, rapidly increasing the temperature of the substrate. Heat is then transferred from the substrate to the fluid. Concomitantly, the fluid transfer unit 30 is operated to transfer fluid from heat exchanger 6 to the first auxiliary heat exchanger 26, thereby transferring heat to this auxiliary heat exchanger. Simultaneously, fluid from the second auxiliary heat exchanger is transferred to heat exchanger 6, while or after which the power supply 40 is switched off, resulting in a temperature drop in the substrate. Heat is then transferred from the fluid (originally from the second heat exchanger) to the substrate. In other words, the fluid from the second heat exchanger 28 that was transferred to heat exchanger 6 is cooled. A second cycle identical to the first cycle is then performed, continuing back and forth.

[0050] Figures 5 and 6 show two devices for generating electrical energy using the heat exchanger of the present invention, which in this case is a pyroelectric heat exchanger.

[0051] The pyroelectric effect is the ability of certain materials to generate a temporary voltage when heated or cooled. The temperature change slightly alters the position of atoms within the crystalline structure, thereby changing the polarity of the material. This change in polarity creates a voltage across the crystal. In general, the pyroelectric effect can be considered the physical opposite to the dielectric caloric effect. This means that the dielectric caloric heat exchangers described above can be used as pyroelectric heat exchangers and vice versa.

[0052] Device 124 is very similar to device 24 of Figure 4. Therefore, it is referred to in the detailed description of Figure 4. Device 124 differs essentially from device 24 of Figure 4 in that the power source has been replaced by an electrical load 140, and the auxiliary heat exchangers have been replaced by a heating source 126 and a cooling source 128. However, it is important to note that in practice, heating source 126 may include an auxiliary heat exchanger or heat reservoir that receives heat. Similarly, a cooling source may include an auxiliary heat exchanger or cooling reservoir that dissipates heat.

[0053] In operation, the fluid transfer unit 130, which may be a reciprocating pump, transfers fluid from the heating source 126 to the heat exchanger 6, causing an increase in the temperature of the dielectric calorific / pyroelectric substrate in the heat exchanger 6 and thereby generating a voltage that charges the electrical load 140. While the electrical load 140 is depicted as comprising a capacitor, such an electrical load can be substantially more complex, e.g., a diode or switching means for controlling charging during one cycle and discharging during the next. During the first cycle, the fluid initially in contact with the dielectric calorific / pyroelectric substrate is transferred toward the cooling source 128. During the second cycle, the fluid is transferred in the opposite direction, i.e., from the cooling source 128 to the heat exchanger 6, causing a decrease in the temperature of the dielectric calorific / pyroelectric substrate in the heat exchanger 6. The electrical load is configured to maintain its charge or transfer its charge to a connected power consumer. In the subsequent third cycle, which is identical to the first cycle, the fluid is transferred from the heating source 126 to the heat exchanger 6, thereby further charging the electrical load 140.

[0054] The thermodynamic cycle described herein above is the Stirling thermodynamic cycle.

[0055] Device 224 of Figure 6 operates on the same principle as device 124 of Figure 5, but to produce successive temperature increases and decreases in the dielectric calorific substrate, the fluid is moved in the same direction but alternately past a heating and cooling source, instead of moving back and forth. It continuously increases and decreases the electric field, resulting in a pulsed power signal. In addition, an external electric field is intermittently applied to the capacitor during pre-heating.

[0056] The fluid transfer unit includes a pump 230 and selector valves 236 and 238. The selector valves 236 and 238 are designed to selectively allow fluid flow through either the heating source 226 or the cooling source 228. While the pump 230 circulates the fluid in the same direction, the valves 236 and 238 are operated sequentially to allow the fluid to alternately pass through the heating source 226 or the cooling source 228. The valves 236 and 238 may be three-way valves with two positions that selectively fluidly connect one of two ports to a third port, the two ports being fluidly connected to the heating and cooling sources, and the third port being fluidly connected to the heat exchanger 6. These valves are well known and widely available commercially.

[0057] The resulting pulsed power signal is similar to that in device 124 of FIG.

[0058] However, electrical load 240 differs somewhat from electrical load 140 in device 124 of FIG. 5 in that a power source is present to apply a voltage to the capacitor intermittently before each heating cycle step.

[0059] The thermodynamic cycle described herein above is the Olsen thermodynamic cycle.

Claims

1. A heat exchanger (6), at least one elongated substrate (10) made of electrocaloric or pyroelectric material and forming at least one channel (14) for a fluid; at least two electrodes (16, 18) at two laterally opposite ends of at least one of said substrates (10); a housing (20) enclosing at least one of said substrates (10) and at least two of said electrodes (16, 18) and provided with at least one fluid connection port (20.1, 20.2); The heat exchanger (6) 1. A heat exchanger (6) characterized in that the housing consists of a heat-shrinkable flexible tube (20) that is shrunk onto at least one of the substrates (10) to form at least one of the fluid connection ports (20.1, 20.2).

2. 2. The heat exchanger (6) of claim 1, wherein the heat shrinkable flexible tube (20) fits tightly to the at least one substrate (10).

3. 3. A heat exchanger (6) according to claim 1 or 2, wherein the at least one channel (14) for a fluid presents a main direction along which the heat-shrinkable flexible tube (20) extends.

4. The heat exchanger (6) according to any one of claims 1 to 3, further comprising electrical leads (36, 38) connected to at least two of the electrodes (16, 18) and extending between at least one outer surface of at least one of the substrates (10) and an inner surface of the heat-shrinkable flexible tube (20).

5. 5. The heat exchanger (6) of claim 4, wherein the electrical leads (36, 38) extend out of the shrinkable flexible tube (20) through at least one of the fluid connection ports (20.1, 20.2).

6. The heat exchanger (6) according to any one of the preceding claims, further comprising at least one hose (32, 34) inside each of said at least one fluid connection port (20.1, 20.2).

7. 7. The heat exchanger (6) according to claim 6, wherein at least one of the hoses (32, 34) is glued to a corresponding fluid connection port (20.1, 20.2).

8. 8. The heat exchanger (6) according to claim 1, wherein the at least one substrate (10) is made of a single substrate (10), and spacers (22) are provided on two opposite faces of the single substrate (10) so as to form, together with the shrinkable flexible tubes (20), two of the at least one channels (14) for the fluid.

9. The heat exchanger (6) according to any one of claims 1 to 7, wherein the at least one substrate (10) is made up of at least two substrates (10) stacked on top of each other, thereby forming at least one channel (14) for a fluid between the at least two substrates.

10. 10. The heat exchanger (6) of claim 9, wherein each of the at least two electrodes (16, 18) is formed by electrically connecting together corresponding opposite ends of at least two of the substrates (10).

11. 11. The heat exchanger (6) according to claim 9 or 10, wherein the at least two substrates (10) are spaced from each other by spacers (12) arranged at two opposite ends of the at least two substrates (10).

12. 12. The heat exchanger (6) according to claim 11, wherein the spacers (12) extend along a main direction of the at least one channel (14) for a fluid.

13. 13. A heat exchanger (6) according to claim 11 or 12, wherein additional spacers (22) are provided on two opposite sides of the stack (8) of at least two of the substrates (10), thereby forming, together with the shrinkable flexible tube (20), two of the at least one channel (14) for the fluid.

14. A device (24) for heating and / or cooling, a dielectric mass heat exchanger (6) with a first fluid connection port (20.1) and a second fluid connection port (20.2) opposite said first fluid connection port (20.1); a first auxiliary heat exchanger (26) fluidly connected to said first fluid connection port (20.1); a second auxiliary heat exchanger (28) fluidly connected to said second fluid connection port (20.2); a fluid transfer unit (30) configured to transfer fluid back and forth from the dielectric calorific heat exchanger (6) to the first auxiliary heat exchanger (26) and from the dielectric calorific heat exchanger (6) to the first auxiliary heat exchanger (26); a power supply (40) configured to intermittently turn on and off power supplied to the dielectric calorific heat exchanger (6) while the fluid transfer unit (30) moves fluid back and forth; The device (24) A device (24), characterized in that the dielectric calorific heat exchanger (6) is according to any one of claims 1 to 13.

15. said device (24) if it does not comprise said at least one hose (32, 34); a first hose (32) extending inside the first fluid connection port (20.1) and fluidly connected to the first auxiliary heat exchanger (26); a second hose (34) extending inside the second fluid connection port (20.2) and fluidly connected to the second auxiliary heat exchanger (28); The device (24) of claim 14 further comprising:

16. A device (124; 224) for generating electrical energy, comprising: a pyroelectric heat exchanger (6); a heat source (126; 226); a cooling source (128; 228); a fluid transfer unit (130; 230, 236, 238) configured to transfer fluid sequentially from the heating source (126; 226) to the pyroelectric heat exchanger (6) and from the cooling source (128; 228) to the pyroelectric heat exchanger (6); an electrical load (140; 240) configured to collect electrical charge from the pyroelectric heat exchanger (6) while the fluid transfer unit (130; 230, 236, 238) continuously transfers fluid; The device (124; 224) A device (124; 224), characterized in that the pyroelectric heat exchanger (6) is according to any one of claims 1 to 13.

17. 17. The device (124) of claim 16, wherein the fluid transfer unit comprises a reciprocating pump (130), the reciprocating pump (130), the heating source (126), and the cooling source (128) are fluidly connected in series to each other to form a branch circuit, the branch circuit being fluidly connected to a first fluid connection port (20.1) of the pyroelectric heat exchanger (6) and a second fluid connection port (20.2) in the pyroelectric heat exchanger (6) opposite the first fluid connection port (20.1).

18. 17. The device (224) of claim 16, wherein the fluid transfer unit comprises a pump (230), a first selection valve (236) and a second selection valve (238), wherein the heating source (226) and the cooling source (228) are arranged in parallel to form a closed circuit and are fluidly connected to the pyroelectric heat exchanger (6) and the pump (230) via the first and second selection valves (236; 238), wherein the fluid circulating through the closed circuit selectively passes through the heating source (226) or the cooling source (228).

19. A method for manufacturing a heat exchanger (6), comprising the steps of: (a) providing at least one elongated substrate (10) made of electrocaloric or pyroelectric material and forming at least one channel (14) for a fluid; (b) forming at least two electrodes (16, 18) on two laterally opposite ends of at least one of said substrates (10); (c) providing a housing (20) enclosing at least one of said substrates (10) and at least two of said electrodes (16, 18) and provided with at least one fluid connection port (20.2, 20.2), The method comprises:

10. The method of claim 1, wherein step (c) comprises inserting at least one of said substrates (10) into a housing consisting of a heat-shrinkable flexible tube (20), and then heating said heat-shrinkable flexible tube (20) so that it shrinks onto said at least one substrate (10), forming at least one fluid connection port (20.1, 20.2).

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