Dielectric and / or pyroelectric heat exchanger with improved housing

Abstract

The present invention is directed to a heat exchanger (6). The heat exchanger (6) comprises at least two substrates (10) made of a dielectric calorific and / or pyroelectric material stacked on top of each other to form at least one channel (14) for a fluid between the at least two substrates (10), at least two electrodes (16, 18) at two opposite ends of the at least two substrates (10), and a housing (20) that encloses the stack (8) of at least two substrates (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 is made of a heat-shrinkable flexible tube (20) that shrinks onto the stack (8) of at least two electrodes (10) to form the at least one fluid connection port (20.1, 20.2).

Description

Technical Field

[0001] The present invention to be described hereinafter originated within the 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 electrocaloric effect.

Background Art

[0003] The electrocaloric effect is a phenomenon in which a substance exhibits a reversible temperature change in an applied electric field. It is often considered to be physically opposite to the pyroelectric effect. It should not be confused with the magnetocaloric effect, which requires a large magnetic field and a strong and expensive magnet, or the thermoelectric effect (especially the Peltier effect). The thermoelectric effect is such that a temperature difference occurs when an electric current is driven through an electrical connection involving two dissimilar conductors. The basic mechanism of the electrocaloric effect results from the voltage causing the entropy of the system to increase or decrease.

[0004] The published prior art patent document, Soviet Patent Invention No. 840621 (SU840621), discloses a refrigeration or cooling generation device using the dielectric calorific effect. The device comprises a central heat exchanger in which plates made of dielectric calorific material are stacked. These plates are spaced apart from each other to form a series of parallel fluid channels between the plates. The stack of dielectric calorific plates is enclosed by a housing that provides two opposite fluid connection ports. The opposite ends of the stack of dielectric calorific plates are in contact with two electrodes connected to a power source. Auxiliary heat exchangers are fluid-connected to each of the two opposite fluid connection ports. Reciprocating positive displacement pumps are fluid-connected to each of the two auxiliary heat exchangers, and the electrodes move the 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, with the power supply being alternately turned on and off.

[0005] The functional principle of the above device is as follows: When power is supplied to the dielectric calorific plate, the temperature of the dielectric calorific plate rises, and the fluid moves from the first auxiliary heat exchanger to the main heat exchanger, thereby heating the fluid. The fluid then moves 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 as a result of heat transfer to the fluid moving to the first heat exchanger and the release of the electric field. Furthermore, also incidentally, the fluid in the second auxiliary heat exchanger moves to the main heat exchanger and receives heat from it. The fluid then moves as in the first movement, i.e., back to the second heat exchanger, while the power supply to the dielectric calorific plate is turned on again for the next cycle. The first heat exchanger exhibits a rising temperature and can thereby supply heat, i.e., heat the medium, while the second heat exchanger exhibits a falling temperature and can thereby receive heat, i.e., cool the medium.

[0006] In the above teaching, the temperature difference achieved in a central heat exchanger is limited to, for example, a few degrees Celsius or a few Kelvins, and is periodic. This means that adequate insulation is necessary. However, the structure of the central heat exchanger in the above teaching exhibits high thermal inertia and insufficient insulation, thereby reducing the achievable temperature difference. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Soviet Patent No. 840621 (SU840621) [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] This invention addresses a technical problem in providing a heat exchanger with improved achievable temperature difference. [Means for solving the problem]

[0009] The present invention aims to provide a heat exchanger comprising: at least one substrate made of dielectric calorific and / or pyroelectric material and forming at least one channel for a fluid; at least two electrodes at two opposite ends of this at least one substrate; and a housing enclosing the at least one substrate and the at least two electrodes and provided with at least one fluid connection port. The housing is made of a thermally shrinkable flexible tube that shrinks over the at least one substrate to form at least one fluid connection port.

[0010] At least one substrate can be composed 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 tube fits snugly to at least one substrate.

[0012] According to a preferred embodiment, at least one channel for the fluid indicates a principal direction along which a thermally shrinkable flexible tube extends.

[0013] According to a preferred embodiment, at least one substrate has two transverse ends having at least two electrodes.

[0014] According to a preferred embodiment, the heat exchanger further comprises electrical conductors, which are connected to at least two electrodes and extend between at least one outer surface of at least one substrate and the inner surface of a thermally shrinkable flexible tube.

[0015] According to a preferred embodiment, the electrical conductor extends out of the retractable 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 at least one fluid connection port, each of which is located within the fluid connection port.

[0017] According to a preferred embodiment, at least one of these hoses is bonded to a corresponding fluid connection port.

[0018] At least one channel can be formed inside at least one substrate.

[0019] According to a preferred embodiment, at least one substrate consists of a single substrate, and spacers are provided on two opposite faces of the single substrate to form two channels for the fluid, together with a retractable flexible tube.

[0020] According to a preferred embodiment, at least one substrate comprises at least two substrates superimposed on each other, thereby forming at least one channel for fluid between the at least two substrates.

[0021] According to a preferred embodiment, each of at least two electrodes is formed by electrically connecting together corresponding end portions of at least two substrates. This can be done by soldering, application of conductive tape, and / or application of a conductive paste.

[0022] According to a preferred embodiment, at least two substrates are spaced apart from each other by spacers disposed at two end portions in these at least two substrates.

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

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

[0025] The present invention also aims at a device for heating and / or cooling. This device includes a dielectric thermoelectric heat exchanger with a first fluid connection port and a second fluid connection port on the opposite side of this first fluid connection port; a first auxiliary heat exchanger fluid-connected to the first fluid connection port; a second auxiliary heat exchanger fluid-connected to the second fluid connection port; a fluid moving unit configured to move fluid reciprocally from the dielectric thermoelectric heat exchanger to the first auxiliary heat exchanger and from the dielectric thermoelectric heat exchanger to the first heat exchanger; and a power supply configured to intermittently turn on and off the power supply to the dielectric thermoelectric heat exchanger while the fluid moving unit moves the fluid reciprocally. Here, the dielectric thermoelectric heat exchanger is according to the present invention.

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

[0027] The present invention also aims at a device for generating electrical energy. This device includes: a pyroelectric heat exchanger; a heating source; a cooling source; a fluid moving unit configured to continuously move 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 accumulate charge from the pyroelectric heat exchanger while the fluid moving unit continuously moves the fluid. Here, 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 supply an electric field to the capacitor before each movement of the fluid from the heating source to the pyroelectric heat exchanger.

[0029] According to a preferred embodiment, the fluid moving unit includes a reciprocating pump. The reciprocating pump, the heating source, and the cooling source are fluid-connected in series with each other to form a branched circuit. This branched circuit is fluid-connected to a first fluid connection port of the pyroelectric heat exchanger (6) and a second fluid connection port in the pyroelectric heat exchanger on the opposite side of the first fluid connection port.

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

[0031] The present invention also aims at a method for manufacturing a heat exchanger, comprising the following steps: (a) providing at least one substrate made of dielectric calorific and / or pyroelectric material to form at least one channel for a fluid; (b) forming at least two electrodes at two opposite ends of at least one substrate; and (c) providing a housing enclosing at least one substrate and at least two electrodes and having at least one fluid connection port. Step (c) comprises inserting at least one substrate into a heat-shrinkable flexible tube, then heating the heat-shrinkable flexible tube to shrink it over at least one substrate to form 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 implemented in a device for heating and / or cooling, and in a device for generating electrical energy from a heating source and a cooling source. The internal volume of the heat exchanger does not exhibit dead volume, and the plastic material of the thermally shrinkable flexible tube forms a first useful insulating barrier, and the size of this plastic material is very limited. The inventors have found that the housing of the heat exchanger does not need to support any significant pressure or force. For this reason, the present solution is particularly interesting. [Brief explanation of the drawing]

[0033] [Figure 1] This graph illustrates the principle of dielectric calorific value, showing the relationship between temperature and voltage. [Figure 2] This is a cross-sectional view of the heat exchanger according to the present invention. [Figure 3] This is a perspective view of the heat exchanger of the present invention before the heat shrinkage of the shrinkable flexible tubes forms the housing of the heat exchanger. [Figure 4]This is a perspective view of the heat exchanger of the present invention, integrated into a device for heating and / or cooling. [Figure 5] This is a perspective view of the heat exchanger of the present invention, which is integrated into a device for generating electrical energy. [Figure 6] This is a perspective view of the heat exchanger of the present invention, integrated with another device for generating electrical energy. [Modes for carrying out the invention]

[0034] The dielectric caloric effect is an adiabatic and reversible temperature change that occurs in polar materials when an electric field is applied. Large dielectric caloric effects can be realized in ferroelectric materials with perovskite-type structures because their polarity exhibits a large dependence on the temperature approaching the ferroelectric phase transition temperature (Tc), particularly with respect to the composition around the compositional phase boundary (MPB). Furthermore, a thin film of the material PZT (a mixture of lead, titanium, oxygen, and zirconium) shows a strong dielectric caloric reaction, with the material cooling by approximately 12°C due to an electric field change of 480 kV / cm at an ambient temperature of 220°C.

[0035] Figure 1 shows a graph of the temperature change over time in a dielectric caloric material when an electric field is applied. The electric field 2 has a rectangular shape, meaning it is applied at 250 volts for more than 20 seconds. The temperature 4 obtained in the material shows an upper limit, which rises to more than 2°C when the electric field is applied, after the temperature has decreased to its initial value due to material relaxation. Next, when the electric field is removed, this temperature shows a lower limit of approximately the same magnitude as the upper limit. The temperature behavior of the upper and lower limits is used here as the dielectric caloric effect.

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

[0037] The heat exchanger 6 comprises a stack 8 of base plates 10, which are plates separated from each other by spacers 12 to form fluid channels 14 between the base plates 10. The base plates 10 are made of a dielectric calorific material, such as any one described above, or any other known to those skilled in the art. The fluid channels 14 are parallel and extend along the main direction of the heat exchanger, perpendicular to the plane of the cross-sectional view. As is obvious, the spacers 12 are positioned adjacent to the lateral edges of the base plates 10. The spacers may exhibit an adhesive layer for bonding onto the base plates 10, thereby enabling the formation of a stable stack 8 of the base plates 10.

[0038] Referring further to Figure 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 in each substrate 10. The heat exchanger 6 also includes a housing formed by a heat-shrinkable flexible tube 20, which shrinks over the stack 8 of the substrates 10. Heat-shrinkable tubes, or general heat shrinks, are shrinkable plastic tubes commonly used to insulate wires, providing abrasion resistance and environmental protection to stranded and solid wire conductors, connections, joints, and terminations in electrical work. They are usually made of polyolefin and, when heated, shrink radially (not longitudinally) to 1 / 2 to 1 / 6 of their diameter. The heat-shrinkable flexible tube 20, in the shrunk state as illustrated in Figure 2, fits snugly over the stack 8 of the substrates 10, so that the fluid channels 14 between the substrates 10 are the only possible flow channels along the heat exchanger 6.

[0039] As is evident in Figure 2, additional spacers 22 can be provided on opposite outer surfaces of the stack 8 of the substrate 10. More specifically, they can be provided on both outer surfaces of the outer substrate in the stack 8 of the substrate 10 so as to form a fluid channel 14 between the outer surface of each of these two substrates and the corresponding inner surface of the thermally shrinkable flexible tube 20. The additional spacers 22 are also adjacent to the corresponding lateral edges of the substrate 10.

[0040] As an alternative to the stack of base bodies 10 described above, the base body can be a single unit, each having a fluid channel formed inside, i.e., formed on the inside of the base body, and / or spacers can be used on opposite sides of the outside of the base body, as in the spacer 22 described above.

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

[0042] Figure 3 is a perspective view of the heat exchanger 6 according to the present invention, with the heat-shrinkable flexible tube 20 not yet shrunk. It can be seen that the heat-shrinkable flexible tube 20 has an inner circumference that is significantly larger than the outer circumference of the stack 8 of the substrate 10. This allows the stack 8 of the substrate 10 to be easily inserted into the heat-shrinkable flexible tube 20. The heat-shrinkable flexible tube 20 is then heated and shrunk onto the stack 8 of the substrate 10 to fit snugly, as illustrated in Figure 2.

[0043] As is evident in Figure 3, the base 10 can extend along the main direction, which corresponds to the main direction of the heat exchanger 6 and the main direction of the thermally contractible flexible tube 20, while each base 10 can have a series of subsections adjacent to one another along this main direction.

[0044] The method for manufacturing a heat exchanger involves the following steps: (a) The step of stacking substrates together, preferably with spacers, to form a fluid channel between them; (b) The step of forming electrodes at both ends on two opposite sides of the substrate and connecting electrical wires to them; (c) Inserting a stack of substrates with electrical wires attached into a heat-shrinkable flexible tube, and then heating the heat-shrinkable flexible tube to shrink it over the stack to form a fluid connection port, It can include...

[0045] The detailed structure described above is advantageous in that there is no dead volume in the fluid passages, and the walls of the thermally shrinkable flexible tubes provide a good first thermal barrier compared to most current materials used to form the housing, such as metal-based materials. The overall cylindrical outer form of the heat exchanger allows for easy enclosure of the heat exchanger with one or more insulating covers. In that case, the thermal inertia of the heat exchanger is limited to the dielectric calorific value substrate and the thermally shrinkable flexible tubes, while the thermally shrinkable flexible tubes exhibit a reduced magnitude.

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

[0047] The device 24 basically comprises a heat exchanger 6 as shown in Figures 2 and 3 and as 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 that fluidly interconnects the first and second auxiliary heat exchangers 26 and 28 and is configured to move the 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 thermally 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 the corresponding end of the thermally shrinkable flexible tube 20. The heat-shrinkable flexible tube 20, once shrunk on the hose 32, forms a firm connection. Similarly, the second auxiliary heat exchanger 28 is fluidly connected to the heat exchanger 6 by the 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 on the hose 34, forms a firm connection. Adhesives or any other type of sealant can be applied to increase the mechanical strength and / or liquid tightness of the connection.

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

[0049] The operation of the device in Figure 4 is as follows: In the first cycle, the power supply 40 is switched on to supply power to the dielectric calorific value substrate, rapidly increasing the temperature of this substrate. Heat is then transferred from this substrate to the fluid. In conjunction with this, the fluid transfer unit 30 is operated to move the fluid from the heat exchanger 6 to the first auxiliary heat exchanger 26, thereby transferring heat to this auxiliary heat exchanger. Simultaneously, the fluid from the second auxiliary heat exchanger is moved to the heat exchanger 6, while, or afterward, the power supply 40 is switched off, resulting in a temperature decrease 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, which has been moved to the heat exchanger 6, is cooled. Next, the same second cycle as the first cycle is performed and continues in a reciprocal manner.

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

[0051] The pyroelectric effect is the ability of certain materials to generate a temporary voltage when heated or cooled. Temperature changes slightly alter the positions of atoms within the crystal structure, thereby altering the material's polarity. This change in polarity generates a voltage across the crystal. Generally, the pyroelectric effect can be considered the physical inverse of 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 in Figure 4. Therefore, it is referred to in the detailed description of Figure 4. Device 124 is basically different from device 24 in Figure 4 in that the power source is replaced by an electrical load 140, and the auxiliary heat exchanger is replaced by a heat source 126 and a cooling source 128. However, it is important to note that in practice the heat source 126 may include an auxiliary heat exchanger or heat reservoir that receives heat. Similarly, the cooling source may include an auxiliary heat exchanger or cooling reservoir that dissipates heat.

[0053] In operation, a fluid transfer unit 130, which can be a reciprocating pump, moves fluid from the heating source 126 to the heat exchanger 6, causing an increase in the temperature of the dielectric calorific value / pyroelectric substrate in the heat exchanger 6, thereby generating a voltage to charge the electrical load 140. The electrical load 140 is represented as comprising a capacitor, and such an electrical load can be substantially more complex, for example, a diode, or a switching means for controlling charging in one cycle and discharging in the next. During the first cycle, the fluid that was initially in contact with the dielectric calorific value / pyroelectric substrate is moved toward the cooling source 128. During the second cycle, the fluid is moved 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 value / pyroelectric substrate in the heat exchanger 6. The electrical load is configured to maintain its charge or to send that charge to a connected power consumer. In the next third cycle, which is the same as the first cycle, the fluid is moved from the heating source 126 to the heat exchanger 6, thereby further charging the electrical load 140.

[0054] In this specification, the thermodynamic cycle described above is Stirling's thermodynamic cycle.

[0055] Device 224 in Figure 6 operates on the same principle as device 124 in Figure 5, but instead of the fluid moving back and forth to produce a continuous temperature rise and fall in the dielectric calorific substrate, it is moved by passing it in the same direction but alternately through the heating and cooling sources. This 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 before heating.

[0056] The fluid transfer unit comprises a pump 230 and selector valves 236 and 238. The selector valves 236 and 238 are designed to selectively allow fluid flow through either a heating source 226 or a cooling source 228. While the pump 230 circulates the fluid in the same direction, the valves 236 and 238 are operated continuously to allow the fluid to continuously pass alternately through either the heating source 226 or the cooling source 228. The valves 236 and 238 can be three-way valves with two positions, one of which is selectively connected to a third port; the two ports are connected to the heating and cooling sources; and the third port is 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 of device 124 in Figure 5.

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

[0059] In this specification, the thermodynamic cycle described above is the Olsen thermodynamic cycle.

Claims

1. A heat exchanger (6), At least one 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) is 1. A heat exchanger (6), characterized in that said housing is made of a heat shrinkable flexible tube (20) and is shrunk onto at least one of said substrates (10) to form at least one of said fluid connection ports (20.1, 20.2).

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

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

5. 5. The heat exchanger (6) of claim 4, wherein the electrical leads (36, 38) extend outside 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 ports (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. The heat exchanger (6) according to any one of claims 1 to 7, 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 a 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 one another, 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 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 spacer (12) extends along a main direction of at least one of the channels (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 faces of the stack (8) of at least two of said substrates (10), thereby forming, together with said shrinkable flexible tubes (20), two of said at least one channel (14) for a 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, opposite said first fluid connection port (20.1), a second fluid connection port (20.2); 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 mass heat exchanger (6) to the first auxiliary heat exchanger (26) and from the dielectric mass heat exchanger (6) to the first auxiliary heat exchanger (26); a power source (40) configured to intermittently turn on and off electrical power supplied to the dielectric mass heat exchanger (6) while the fluid movement unit (30) moves fluid back and forth; The device (24) comprises: A device (24), characterized in that the dielectric heat exchanger (6) is according to any one of claims 1 to 13.

15. When the at least one hose (32, 34) is provided, the at least one hose (32, 34) is provided, otherwise the device (24) is provided, 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 heating source (126; 226); A cooling source (128; 228); a fluid transfer unit (130; 230, 236, 238) configured to transfer fluid successively 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) comprises 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 with 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 to a second fluid connection port (20.2) in the pyroelectric heat exchanger (6) opposite the first fluid connection port (20.1).

18. 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), the heating source (226) and the cooling source (228) being arranged in parallel and fluidly connected to the pyroelectric heat exchanger (6) and the pump (230) via the first and second selection valves (236; 238) to form a closed circuit, 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 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:

11. The method of claim 10, wherein said step (c) comprises inserting at least one of said substrates (10) into a heat shrinkable flexible tube (20) and then heating said heat shrinkable flexible tube (20) so as to shrink onto said at least one substrate (10) to form at least one fluid connection port (20.1, 20.2).

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