Method and apparatus for operating cyclic process-based systems

Abstract

A method for operating cyclic process-based systems, with a hot-side reservoir (1) and a cold-side reservoir (2) for a fluid (3), and at least one heat exchanger unit (4) with mechanocaloric material, wherein the mechanocaloric material of the heat exchanger unit (4) is actively connected to the fluid (3) such that heat is transferred between the mechanocaloric material and the fluid (3). It is essential that the transfer of heat between the mechanocaloric material and the fluid (3) takes place essentially by latent heat transfer. A corresponding heat-transfer unit (4) and a corresponding apparatus are also provided.

Claims

1. A method for operating cyclic-process-based systems having a hot-side reservoir (1, 11, 21) and a cold-side reservoir (2, 12, 22) for a fluid (3) and at least one heat exchanger unit (4) with a mechanocaloric material, the cyclic-process-based system being a heat pump having at least two heat exchanger units (14.1, 14.2), including the at least one heat exchanger unit, the heat exchanger units having the mechanocaloric material, the method comprising: arranging the mechanocaloric material of the heat exchanger unit (4) to be operatively connected to the fluid (3) in a gas-tight fluid circuit, such that a heat transfer takes place between mechanocaloric material and fluid (3), transferring heat between mechanocaloric material and the fluid (3) substantially by latent heat transfer via evaporation heat and condensation heat of the fluid (3), and alternately opening and closing a hot-side valve (7, 17) and a cold-side valve (8, 18) with respect to one another.

2. The method as claimed in claim 1, further comprising: generating a change in shape of the mechanocaloric material by a mechanical stress in the mechanocaloric material, and generating a change in temperature of the mechanocaloric material by at least one of a tensile or compressive loading of the mechanocaloric material.

3. The method as claimed in claim 1, wherein the heat exchanger units having the mechanocaloric material, and using potential energy contained in a compression of the mechanocaloric material of a first one of the heat exchanger units (14.1) from elastic deformation of the mechanocaloric material for compression of the mechanocaloric material of a second one of the heat exchanger units (14.2).

4. The method as claimed in claim 1, wherein the alternately opening and closing the hot-side valve (7, 17) and the cold-side valve (8, 18) with respect to one another is carried out with an alternation frequency higher than 10 Hz.

5. The method as claimed in claim 1, further comprising at least one of forming the mechanocaloric material as a porous material, with a honeycomb structure, as a pin structure or as a spring, with a structuring or a coating.

6. The method as claimed in claim 1, further comprising providing a fluid circuit for the fluid (8), including a fluid return line (6, 16), and the fluid circuit includes the hot-side reservoir (1, 11, 21), the cold-side reservoir (2, 12, 22), the hot-side valve (7, 17), the cold-side valve (8, 18), the mechanocaloric material, and the fluid return line (6, 16) and is a pressure-tight system, and configuring the pressure-tight system such that the heat transfer from the fluid (8) to the mechanocaloric material takes place by latent heat.

7. The method as claimed in claim 6, further comprising removing substantially all foreign gases other than the fluid (3) from the pressure-tight system.

8. The method as claimed in claim 6, wherein the hot-side valve (7, 17) is arranged in the fluid circuit between the hot-side reservoir (1, 11, 21) and the mechanocaloric material, and the method further comprising heating of the mechanocaloric material causing the hot-side valve (7, 17) to be opened, and the cold-side valve (8, 18) is arranged in the fluid circuit between the cold-side reservoir (2, 12, 22) and the mechanocaloric material, and the method further comprising cooling of the mechanocaloric material causing causes the cold-side valve (8, 18) to be opened.

9. The method of claim 8, further comprising arranging the cold-side reservoir (2, 12, 22), the hot-side reservoir (1, 11, 21), and the mechanocaloric material in a closed-off volume (29) in which heat transport takes place by convection of the fluid (3) that is evaporated, and return transport of the fluid (3) that is evaporated takes place.

10. The method of claim 9, further comprising providing the closed-off volume (29) with at least one of a fluid-phobic coating or structuring in a region of the hot-side reservoir (2) or at least one of a fluid-philic coating or structuring in a region of the cold-side reservoir (2), or both.

11. The method of claim 9, further comprising providing the closed-off volume (29) with at least one of a hydrophilic coating or structuring in a region of the hot-side reservoir (2) or at least one of a hydrophobic coating or structuring in a region of the cold-side reservoir (2), or both.

12. The method of claim 9, further comprising providing the closed-off volume (29) with at least one of an oleophilic coating or structuring in a region of the hot-side reservoir (2) or at least one of an oleophobic coating or structuring in a region of the cold-side reservoir (2), or both.

13. The method of claim 1, further comprising providing a heat pump and a piston system (5, 15, 19) as the mechanical stress generator that generates a mechanical stress (5, 15, 19) for at least one of tensile or compressive loading.

14. The method of claim 1, further comprising providing a heat engine having the at least two heat exchanger units (14.1, 14.2) with the mechanocaloric material.

15. The method of claim 1, further comprising providing a heat engine having the at least two heat exchanger units (14.1, 14.2) with the mechanocaloric material.

16. The method of claim 1, wherein the alternately opening and closing of the hot-side valve (7, 17) and the cold-side valve (8, 18) with respect to one another is with an alternation frequency of between 0.1 Hz and 10 kHz.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further preferred features and embodiments of the method according to the invention and of the device according to the invention will be discussed below on the basis of exemplary embodiments and the figures, in which:

(2) FIG. 1 is a schematic illustration of a first exemplary embodiment of a device according to the invention as a heat pump;

(3) FIG. 2 is a schematic illustration of a second exemplary embodiment of a device according to the invention as a heat pump;

(4) FIG. 3 is a schematic illustration of a third exemplary embodiment of a device according to the invention as a heat engine;

(5) FIGS. 4A-4C show a schematic illustration of the fluid return line;

(6) FIG. 5 is a schematic illustration of the embodiment of FIG. 4B as a jumping-drop thermal diode for unidirectional heat transport; and

(7) FIGS. 6A-6C show a schematic illustration of the mechanocaloric material; and

DETAILED DESCRIPTION

(8) In FIGS. 1 to 6C, the same reference designations are used to denote identical elements or elements of identical action.

(9) FIG. 1 is a schematic illustration of a heat pump as a first exemplary embodiment of a device according to the invention.

(10) In the present case, the device is designed as a heat pump and is designed with a hot-side reservoir 1 and a cold-side reservoir 2 for a fluid 3. In the present case, water is used as fluid 3. In the present case, the hot-side reservoir 1 has a temperature of 150° C. and a prevailing pressure of 4.7 bar. In the present case, the cold-side reservoir 1 has a temperature of 20° C. and a prevailing pressure of 0.023 bar.

(11) A heat exchanger unit 4 with mechanocaloric material is arranged between hot-side reservoir 1 and cold-side reservoir 2. In the present case, the mechanocaloric material 4 is a nickel-titanium alloy.

(12) In the present case, the heat pump has a fluid circuit for the fluid 3. For this purpose, a fluid return line 6 is arranged between hot-side reservoir 1 and cold-side reservoir 2. The fluid circuit thus comprises hot-side reservoir 1, cold-side reservoir 2, hot-side valve, cold-side valve, the region of the heat exchanger unit 4, and the fluid return line 6. The fluid circuit is designed as a pressure-tight system by virtue of substantially all foreign gases (that is to say all gases with the exception of the fluid 3) having been removed from the pressure-tight system.

(13) In the fluid circuit, a hot-side valve 7 is arranged between the region of the heat exchanger unit 4 and the hot-side reservoir 1, and a cold-side valve 8 is arranged between the region of the heat exchanger unit 4 and the cold-side reservoir 2. In the present case, the hot-side valve 7 and the cold-side valve 8 are designed as pressure-controlled valves. The respective differential pressure at which the two valves open is adjustable, and in the present case is 10 mbar.

(14) In the present case, as means for generating a mechanical stress in the mechanocaloric material, the heat pump has means for exerting tensile or compressive loading on the mechanocaloric material by a piston system 5. The piston system 5 comprises a cylinder 5a, in which the mechanocaloric material 4 is arranged, and a piston 5b, and is in the present case designed with an eccentric for compressing the mechanocaloric material. The maximum exertion of pressure is in the present case 500 MPa.

(15) The mechanocaloric material of the heat exchanger unit 4 is arranged so as to be operatively connected to the fluid 3, such that heat can be transferred between fluid 3 and mechanocaloric material. For this purpose, the fluid flows through the mechanocaloric material of the heat exchanger unit 4. The pressure-type system is, by the temperature of the hot-side reservoir 1, the temperature of the cold-side reservoir 2 and the prevailing pressure of the fluid 3, designed such that the heat transfer from the fluid 3 to the mechanocaloric material of the heat exchanger unit 4 takes place by latent heat.

(16) During the operation of the heat pump, the following method steps are performed repeatedly:

(17) A Compression of the mechanocaloric material of the heat exchanger unit 4 by the piston system 5.

(18) The piston 5b is moved into the cylinder 5a by the eccentric. As a result, the mechanocaloric material of the heat exchanger unit 4 is compressed. The compression gives rise to a phase transition in the mechanocaloric material, and the temperature of the mechanocaloric material increases.

(19) B Heat transfer from the mechanocaloric material to the fluid 3 by latent heat (evaporation heat).

(20) The surrounding fluid 3 warms up as a result of the contact with the mechanocaloric material of the heat exchanger unit 4, and evaporates. As a result, the pressure in the region of the heat exchanger unit 4 increases.

(21) C Opening of the hot-side valve 7.

(22) If the pressure in the region of the heat exchanger unit 4 exceeds the differential pressure of the hot-side valve, the hot-side valve 7, which controls the connection to the hot-side reservoir 1, opens. The gaseous fluid 3 flows into the hot-side reservoir 1 and, here, releases the stored heat.

(23) Active control of the valves may alternatively also be performed.

(24) As a result of the heat transfer to the fluid 3, the mechanocaloric material has assumed the ambient temperature.

(25) D The compression pressure on the mechanocaloric material of the heat exchanger unit 4 is withdrawn.

(26) The piston 5b is moved out of the cylinder 5a by the eccentric. This gives rise to the reverse phase transition in the mechanocaloric material, and the temperature of the mechanocaloric material decreases.

(27) E Heat transfer from the fluid 3 to the mechanocaloric material by latent heat (condensation heat).

(28) The substantially vaporous fluid 3 in the region of the heat exchanger unit 4 condenses on the mechanocaloric material, such that here, a heat transfer takes place by latent heat.

(29) F Opening of the cold-side valve.

(30) As a result of the condensation of the fluid 3, the pressure in the region of the heat exchanger unit 4 decreases. If the pressure in the region of the heat exchanger unit 4 falls below the differential pressure of the cold-side valve, the cold-side 8, which controls the connection to the cold-side reservoir 2, opens.

(31) New, cold fluid 3 flows in from the cold-side reservoir 2, which fluid then, in a further cycle, warms up and can be transported to the hot-side reservoir 1.

(32) Via the fluid return line 6, the fluid 3 is transported from the hot-side reservoir 1 back to the cold-side reservoir 2. To maintain the pressure difference between hot-side reservoir 1 and cold-side reservoir 2, a throttle (not illustrated) is installed into the fluid return line 6, analogously to classic heat pumps based on compressors. This throttle ensures a pressure drop of 4.7 bar in the presence of an adequate fluid flow of >1 g/s for a heat pump power of 2 kW.

(33) The schematic illustration of FIG. 1 will be described in more detail below on the basis of a further alternative specific implementation of an air-conditioning device. For this purpose, as a heat exchanger unit, the mechanocaloric material Nitinol 4 is integrated as hollow rods (cf. FIG. 6a) into a gas-tight (pressure-tight) cylinder 5a.

(34) Here, the hollow rods are situated parallel to one another in a vertical orientation in the gas-tight cylinder 5a. The cylinder 5a can be subjected, by a hydraulic press, to a force {right arrow over (F)}, which leads to an exertion of pressure on the hollow rods 4, in the present case of up to 750 MPa. As a result, the hollow rods are warmed up, and are correspondingly cooled down again in the event of the force being withdrawn.

(35) Recessed in the gas-tight cylinder 5a are two overpressure valves 7, 8, which separate the hollow rods comprised of mechanocaloric material 4 from the hot-side reservoir 1 and cold-side reservoir 2. In the system comprised of hot-side reservoir 1, cold-side reservoir 2 and cylinder 5a, all residual gases with the exception of the fluid, in the present case ethanol, have been evacuated.

(36) The gas-tight cylinder 5a is connected via the cold-side valve 8 to the cold-side reservoir 2. The cold-side valve 8 is designed as a passive overpressure valve which, in a forward direction, opens already in the presence of small pressure differences of <<1 mbar, whereas said overpressure valve prevents a fluid flow in a reverse direction. In the same way, and overpressure valve 8 is situated in the connection to the hot-side reservoir 1.

(37) As a result of application of an external force to the gas-tight cylinder 5a, the hollow rods 4 warm up, and the fluid that is present in liquid form on said hollow rods evaporates. The overpressure valve 7 in the direction of the hot side opens, and as a result of the evaporation of the fluid, thermal energy is transferred from the hollow rods comprised of mechanocaloric material 4 to the hot-side reservoir 1 by latent heat transfer.

(38) In the event of the external force being withdrawn, the hollow rods 4 cool down. As a result, gaseous fluid condenses on the hollow rods, and the vapor pressure in the gas-tight cylinder 5a decreases. This leads to the opening of the overpressure valve 8 in the direction of the cold-side reservoir 2. In this stage of the process, the temperature in the gas-tight cylinder 2a with the hollow rods comprised of mechanocaloric material 4 is lower than in the cold-side reservoir 2. The fluid 3 in the cold-side reservoir 2 evaporates, whereby the cold-side reservoir cools down.

(39) With every further cycle, thermal energy is exchanged between hollow rods and fluid by latent heat transfer, such that heat transport from the cold side to the hot side occurs. Through cyclic repetition of this process, an ever greater amount of thermal energy is then transported from the cold-side reservoir into the hot-side reservoir. The more quickly this process is repeated, that is to say the higher the cycle frequency is, the greater is the effective level of cooling power.

(40) In the case of 18 hollow rods comprised of Nitinol (Ni55/Ti45) with an outer diameter of 2.4 mm, a wall thickness of 0.5 mm and a length of 10 mm being used, in the case of an exertion of pressure of 700 MPa with a cycle frequency of 0.25 Hz, a temperature difference between hot-side reservoir and cold-side reservoir of approximately 15° is achieved. This corresponds, for example, to a temperature of the hot-side reservoir of approximately 35 degrees (pressure 137 mbar) and a temperature of the cold-side reservoir of approximately 20 degrees (pressure 58 mbar). Use as an air-conditioning system or the like is possible in this temperature range.

(41) The described heat pump can also, with the substantially identical device, be operated as a heat engine. For this purpose, the hot-side reservoir and cold-side reservoir must be interchanged in terms of their functionality. The control of the valves is then performed actively.

(42) FIG. 2 is a schematic illustration of a heat pump as a second exemplary embodiment of a device according to the invention.

(43) To avoid repetitions, only the differences between the figures will be discussed below.

(44) In the present case, the device is designed as a heat pump and is designed with a hot-side reservoir 1 and a cold-side reservoir 2 for a fluid 3. In the present case, two heat exchanger units 4.1, 4.2 with mechanocaloric material are arranged between hot-side reservoir 1 and cold-side reservoir 2. The heat exchanger units 4.1, 4.2 are arranged in the fluid circuit such that they are flowed through separately by the fluid 3, analogously to a parallel connection of resistances in an electrical circuit.

(45) In the fluid circuit, a hot-side valve 7.1 is arranged between the first heat exchanger unit 4.1 and the hot-side reservoir 1, and a cold-side valve 8.1 is arranged between the first heat exchanger unit 4.1 and the cold-side reservoir 2. Likewise, in the fluid circuit, a hot-side valve 7.2 is arranged between the second heat exchanger unit 4.2 and the hot-side reservoir 1, and a cold-side valve 8.2 is arranged between the second heat exchanger unit 4.2 and the cold-side reservoir 2. In the present case, the hot-side valves 7.1, 7.2 and the cold-side valves 8.1, 8.2 are designed as pressure-controlled valves.

(46) As means for exerting tensile and/or compressive loading on the mechanocaloric material, the heat pump has a piston system 5. The piston system 5 comprises a piston 5b, and in the present case is designed as an eccentric for compressing the mechanocaloric material. As counterparts, two cylinders 5a.1, 5a.2 are provided, in which the mechanocaloric material 4.1, 4.2 is arranged in each case.

(47) For the compression of the mechanocaloric material, the piston is moved back and forth between the cylinders 5a.1, 5a.2. The two heat exchanger units 4.1, 4.2 with mechanocaloric material are thus compressed alternately. Here, the potential energy contained in the compression of the mechanocaloric material of the first heat exchanger unit 4.1 is used for the compression of the mechanocaloric material of the second heat exchanger unit 4.2, and vice versa.

(48) The eccentric is optionally designed with a ball bearing (instead of the piston 5b), the central point of which lies outside the shaft axis of the eccentric shaft (not illustrated). The ball bearing is indirectly operatively connected, in the present case in non-positively locking fashion, to the two heat exchanger units 4.1 and 4.2. In the event of a rotation of the shaft, the ball bearing rotates and compresses the two heat exchanger units 4.1 and 4.2 in each case alternately. Here, the compression takes place within the gas-tight volume of the cylinders 5a.1 and 5a.2. Here, the ball bearing is situated between the cylinders 5a.1 and 5a.2 and can act on the heat exchanger units 4.1 and 4.2 through the cylinder, for example via a bellows.

(49) The two heat exchanger units 4.1, 4.2 with mechanocaloric material thus both run through the method described with regard to FIG. 1, but in a time-offset manner.

(50) The opening and closing of the valves 7.1, 7.2, 8.1, 8.2 is controlled by the prevailing pressure conditions, analogously to the situation described with regard to FIG. 1. In this way, active pumps for the fluid 3 can be omitted.

(51) The described heat pump can also, with the substantially identical device, be operated as a heat engine, that is to say with the reverse cyclic process. For this purpose, the hot-side reservoir and cold-side reservoir must be interchanged in terms of their functionality. The control of the valves is then performed actively. As a result of the alternating change in temperature of the two heat exchanger units 4.1, 4.2 with mechanocaloric materials, the heat exchanger units 4.1, 4.2 expand alternately, such that the piston 5b is moved back and forth. This movement can be utilized as mechanical work.

(52) FIG. 3 is a schematic illustration of a third exemplary embodiment of a device according to the invention, which is operable as a heat engine or a heat pump.

(53) In the present case, the device is designed as a heat engine, and is designed with a hot-side reservoir 11 and a cold-side reservoir 12 for a fluid 3. In the present case, to heat exchanger units 14.1, 14.2 with mechanocaloric material are arranged between the hot-side reservoir 11 and cold-side reservoir 12. The heat exchanger units 14.1, 14.2 are arranged in the fluid circuit such that they are flowed through separately by the fluid 3, analogously to a parallel connection of resistances in an electrical circuit. A fluid return line 16 runs between hot-side reservoir 11 and cold-side reservoir 12. This fluid return line is in the present case designed as a tube filled with a wick.

(54) In the fluid circuit, a hot-side valve 17.1 is arranged between the first heat exchanger unit 14.1 and the hot-side reservoir 11, and a cold-side valve 18.1 is arranged between the first heat exchanger unit 14.1 and the cold-side reservoir 12. Likewise, in the fluid circuit, a hot-side valve 17.2 is arranged between the second heat exchanger unit 14.2 and the hot-side reservoir 11, and a cold-side valve 18.2 is arranged between the second heat exchanger unit 14.2 and the cold-side reservoir 12. In the present case, the valves 17.1, 17.2, 18.1, 18.2 are designed as actively controlled valves.

(55) As means for inducing a current from movement, the heat engine has a coil 19 with a magnetizable core 15b. The magnetizable core 15b of the coil 19 is designed as a piston. As counterparts, two cylinders 15a.1, 15a.2 are provided, in which the mechanocaloric material 14.1, 14.2 is arranged in each case. The magnetizable core 15b of the coil 19 is therefore operatively connected to the mechanocaloric material of the two heat exchanger units 14.1, 14.2. Therefore, a change in temperature of the mechanocaloric material of one of the two heat exchanger units 14.1, 14.2 causes a movement of the core 15b in the coil 19 to be generated. The movement of the core 15b in the coil 19 causes an electrical current to be induced in the coil.

(56) If the first hot-side valve 17.1 is opened, the fluid 3 in the gaseous phase which is situated in the hot-side reservoir 11 flows into the region of the first heat exchanger unit 14.1 with the mechanocaloric material. There, the fluid 3 condenses on the mechanocaloric material and thus warms up the mechanocaloric material. Owing to the change in temperature, a phase transition in the mechanocaloric material occurs, and the mechanocaloric material expands. Since the mechanocaloric material is operatively connected to the magnetizable core 15b in the coil 19, said core is pushed out of the cylinder 15a.1.

(57) If, then, the hot-side valve 17.1 is closed and the cold-side valve 18.1 is opened, the pressure in the region of the mechanocaloric material decreases, and the condensed fluid evaporates and, by latent heat transfer, removes evaporation heat from the mechanocaloric material, such that the latter cools. Owing to the change in temperature, the reverse phase transition occurs in the mechanocaloric material, and the mechanocaloric material contracts.

(58) At the same time, the second hot-side valve 17.1 can be opened. The fluid 3 in the gaseous phase situated in the hot-side reservoir 11 thus flows into the region of the second heat exchanger unit 14.2 with the mechanocaloric material. There, the fluid 3 condenses on the mechanocaloric material and thus warms up the mechanocaloric material. Owing to the change in temperature, a phase transition occurs in the mechanocaloric material, and the mechanocaloric material expands. Since the mechanocaloric material is operatively connected to the magnetizable core 15b in the coil 19, said core is pushed out of the cylinder 15a.2.

(59) These two effects are codirectional, and serve to realize a return movement of the magnetizable core 15b in the coil 19.

(60) As a result of the alternating change in temperature of the two heat exchanger units 14.1, 14.2 with mechanocaloric material, the heat exchanger units 14.1, 14.2 expand alternately, such that the magnetizable core 15b is moved back and forth in the coil 19. This movement causes an alternating current to be induced.

(61) Via the fluid return line 16, the fluid 3 is transported from the cold-side reservoir 12 back to the hot-side reservoir 11.

(62) The device described with regard to FIG. 3 may likewise be operated as a heat pump, that is to say with the reverse cyclic process. An electrical energization of the coil 19 causes a movement of the magnetizable core 15b in the coil to be generated. The movement of the magnetizable core 15b in the coil thus causes a compression of the mechanocaloric material, and thus a change in temperature of the two heat exchanger units 14.1, 14.2, such that a change in temperature of the mechanocaloric material is generated.

(63) These changes in temperature may, as described with regard to FIGS. 1 and 2, be transferred in each case to the fluid 3 by latent heat transfer. The heat can then be discharged into the hot-side reservoir by the fluid 3.

(64) FIGS. 4A-4C show a schematic illustration of three details of exemplary embodiments, in particular for the realization of the unidirectional heat transport by means of latent heat (analogously to a thermal diode) with a corresponding fluid return line.

(65) In the present case, the hot-side reservoir 21, the cold-side reservoir 22 and the mechanocaloric material are arranged in a common, close-off volume 29 for the fluid 3. The cold-side reservoir 22 is arranged in one region of the volume 29, and the hot-side reservoir 21 is arranged in an oppositely situated region of the volume 29. The mechanocaloric material of the heat exchanger unit (not illustrated) is arranged between said regions. This means that only the heat exchanger unit, and no further physical separation, is present between called-side reservoir 22 and hot-side reservoir 21. Here, the fluid 3 can flow unhindered through the mechanocaloric material of the heat exchanger unit. Control of the fluid transport is realized by the boundary conditions such as pressure, temperature and gravitational force.

(66) In all three embodiments, the closed-off volume is designed as a thermal diode, which restricts the heat flow to one direction.

(67) FIG. 4A illustrates a first variant. The return transport of the fluid is realized in the present case by means of gravitational force, illustrated by the arrow g, by virtue of the condensed fluid 3 condensing on a surface of the other reservoir 41 and running back into the origin reservoir 40 under the action of the gravitational force g.

(68) A return transport of the condensed fluid 3 is thus realized in order to prevent the origin reservoir 40 of the fluid 3 from drying out. This process is however rather slow and is not independent of position.

(69) FIG. 4B illustrates a second variant. In the present case, the closed-off volume 29 has a superhydrophilic coating in the region of the origin reservoir 40 and has a superhydrophobic coating in the region of the other reservoir 41. The device is thus designed analogously to a “jumping-drop thermal diode”, as described in Boreyko et al., Applied Physics Letter 99.

(70) If the fluid in the closed-off volume evaporates and condenses on the superhydrophobic coating in the region of the other reservoir 41, the condensed droplets, denoted by way of example by 3.1, 3.2 and 3.3, of the fluid 3 are correspondingly repelled by the coating, such that they “jump back” into the superhydrophilic region of the origin reservoir 40. In the present case, the origin reservoir 40 is the hot-side reservoir 21, and the other reservoir 41 The jumping-drop thermal diode functions independently of the position of the diode in space. There is additionally the advantage that the return transport of the condensed fluid 3 can take place quickly.

(71) FIG. 4C schematically illustrates the exemplary embodiments, described with regard to FIGS. 1 to 3, with valve control and external fluid return line 6.

(72) FIG. 5 is a schematic illustration of the variance described in FIG. 4B as a jumping-drop thermal diode for the realization of the unidirectional heat transport by latent heat and the fluid return line. Additionally illustrated is the mechanocaloric material of two heat exchanger units 54.1, 54.2 in the respective closed-off volume 29.1, 29.2. Provided between the two heat exchanger units 54.1, 54.2 is a piston 55b, which is in each case operatively connected to the mechanocaloric material of the two heat exchanger units 54.1, 54.2.

(73) For the compression of the mechanocaloric material, the piston 55b is moved back and forth, as indicated by the double arrow. The two heat exchanger units 54.1, 54.2 with mechanocaloric material are thus compressed alternately.

(74) The two heat exchanger units 54.1, 54.2 with mechanocaloric material thus both run through the method described with regard to FIGS. 1 and 2. The heat transport and the return of the fluid take place as described in FIG. 4b.

(75) FIGS. 6A-6C show a schematic illustration of various embodiments of the mechanocaloric material.

(76) FIG. 6A shows the mechanocaloric material with a pin structure. In the case of the embodiment as a pin structure, in the present case with multiple parallel pins, denoted by way of example by 62a, 62b and 62c, there is the advantage that a stable structure with a large surface area for the heat transfer can be formed in a simple manner.

(77) FIG. 6B shows the mechanocaloric material as a spring 61. The spring structure permits a greater travel owing to the compression of the mechanocaloric material by a piston system. Here, the spring is compressed and stored the potential energy from the compression. Here, in a particularly efficient manner, the potential energy stored in the mechanocaloric material can be returned in order that it can be utilized for a compression of a further heat exchanger unit with mechanocaloric material.

(78) FIG. 6C shows the mechanocaloric material with a honeycomb structure. The individual honeycombs, denoted by way of example by 60a, 60b, 60c, of the honeycomb structure are in the present case of regular hexagonal form. The acting forces of the mechanical stress field during the compressive or tensile loading are distributed homogeneously in the honeycomb structure. This ensures a uniform force distribution and thus a long lifetime of the mechanocaloric material. Owing to the uniform force distribution, it is possible for thin structures, in particular intermediate walls, to be formed between the individual honeycombs. In this way, good heat transport in the material is ensured.